diff --git a/paket.dependencies b/paket.dependencies
index 02b7758..a8cd9bd 100644
--- a/paket.dependencies
+++ b/paket.dependencies
@@ -3,12 +3,13 @@ source http://nuget.org/api/v2
 nuget FAKE
 nuget SourceLink.Fake
 nuget Nuget.CommandLine
-nuget FSharp.Core ~> 3.1.2
+nuget FSharp.Core ~> 4.0.0.1
 nuget Rx-Experimental ~> 2.2.5
 nuget Rx-Main ~> 2.2.5
 nuget Rx-PlatformServices ~> 2.2.5
 nuget Rx-Testing ~> 2.2.5
 nuget NUnit 
 nuget NUnit.Runners 
+nuget FsCheck.NUnit
 nuget FSharp.Formatting
 nuget FSharp.Compiler.Service
diff --git a/paket.lock b/paket.lock
index 6f67970..2ca9162 100644
--- a/paket.lock
+++ b/paket.lock
@@ -1,15 +1,21 @@
 NUGET
-  remote: http://nuget.org/api/v2
+  remote: http://www.nuget.org/api/v2
   specs:
-    FAKE (4.0.3)
-    FSharp.Compiler.Service (1.4.0.1)
-    FSharp.Core (3.1.2.5)
+    FAKE (4.12.2)
+    FsCheck (2.2.4)
+      FSharp.Core (>= 3.1.2.5)
+    FsCheck.Nunit (2.2.4)
+      FsCheck (>= 2.2.4)
+      NUnit (>= 2.6.4 < 2.7.0)
+      NUnit.Runners (>= 2.6.4 < 2.7.0)
+    FSharp.Compiler.Service (2.0.0.2)
+    FSharp.Core (4.0.0.1)
     FSharp.Formatting (2.10.0)
       FSharp.Compiler.Service (>= 0.0.87)
       FSharpVSPowerTools.Core (1.8.0)
     FSharpVSPowerTools.Core (1.8.0)
       FSharp.Compiler.Service (>= 0.0.87)
-    NuGet.CommandLine (2.8.6)
+    NuGet.CommandLine (3.3.0)
     NUnit (2.6.4)
     NUnit.Runners (2.6.4)
     Rx-Core (2.2.5)
@@ -35,4 +41,4 @@ NUGET
       Rx-Main (>= 2.2.5)
     Rx-Testing (2.2.5)
       Rx-Main (>= 2.2.5)
-    SourceLink.Fake (1.0.0)
+    SourceLink.Fake (1.1.0)
diff --git a/src/FSharp.Control.Reactive.fsproj b/src/FSharp.Control.Reactive.fsproj
index 013011c..d3ef53f 100644
--- a/src/FSharp.Control.Reactive.fsproj
+++ b/src/FSharp.Control.Reactive.fsproj
@@ -55,79 +55,35 @@
     <None Include="paket.references" />
   </ItemGroup>
   <ItemGroup>
+    <Reference Include="FSharp.Core, Version=4.4.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
+      <Private>True</Private>
+    </Reference>
     <Reference Include="mscorlib" />
     <Reference Include="System.Numerics" />
   </ItemGroup>
   <Choose>
-    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v2.0' Or $(TargetFrameworkVersion) == 'v3.0' Or $(TargetFrameworkVersion) == 'v3.5')">
-      <ItemGroup>
-        <Reference Include="FSharp.Core">
-          <HintPath>..\packages\FSharp.Core\lib\net20\FSharp.Core.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETCore') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile44')">
-      <ItemGroup>
-        <Reference Include="FSharp.Core">
-          <HintPath>..\packages\FSharp.Core\lib\portable-net45+netcore45\FSharp.Core.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.0' Or $(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
-      <ItemGroup>
-        <Reference Include="FSharp.Core">
-          <HintPath>..\packages\FSharp.Core\lib\net40\FSharp.Core.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
-    <When Condition="($(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0') Or ($(TargetFrameworkProfile) == 'Profile24') Or ($(TargetFrameworkProfile) == 'Profile47')">
-      <ItemGroup>
-        <Reference Include="FSharp.Core">
-          <HintPath>..\packages\FSharp.Core\lib\portable-net45+sl5+netcore45\FSharp.Core.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
-    <When Condition="($(TargetFrameworkIdentifier) == 'WindowsPhone' And ($(TargetFrameworkVersion) == 'v8.0' Or $(TargetFrameworkVersion) == 'v8.1')) Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
-      <ItemGroup>
-        <Reference Include="FSharp.Core">
-          <HintPath>..\packages\FSharp.Core\lib\portable-net45+netcore45+wp8\FSharp.Core.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
-    <When Condition="($(TargetFrameworkIdentifier) == 'WindowsPhoneApp') Or ($(TargetFrameworkProfile) == 'Profile32') Or ($(TargetFrameworkProfile) == 'Profile84') Or ($(TargetFrameworkProfile) == 'Profile111') Or ($(TargetFrameworkProfile) == 'Profile151') Or ($(TargetFrameworkProfile) == 'Profile157') Or ($(TargetFrameworkProfile) == 'Profile259')">
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETCore'">
       <ItemGroup>
-        <Reference Include="FSharp.Core">
-          <HintPath>..\packages\FSharp.Core\lib\portable-net45+netcore45+wpa81+wp8\FSharp.Core.dll</HintPath>
+        <Reference Include="System.Reactive.Core">
+          <HintPath>..\packages\Rx-Core\lib\windows8\System.Reactive.Core.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
       </ItemGroup>
     </When>
-  </Choose>
-  <Choose>
-    <When Condition="$(TargetFrameworkIdentifier) == '.NETCore'">
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.0')">
       <ItemGroup>
         <Reference Include="System.Reactive.Core">
-          <HintPath>..\packages\Rx-Core\lib\windows8\System.Reactive.Core.dll</HintPath>
+          <HintPath>..\packages\Rx-Core\lib\net40\System.Reactive.Core.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.0')">
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
       <ItemGroup>
         <Reference Include="System.Reactive.Core">
-          <HintPath>..\packages\Rx-Core\lib\net40\System.Reactive.Core.dll</HintPath>
+          <HintPath>..\packages\Rx-Core\lib\net45\System.Reactive.Core.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -160,10 +116,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
       <ItemGroup>
         <Reference Include="System.Reactive.Core">
-          <HintPath>..\packages\Rx-Core\lib\net45\System.Reactive.Core.dll</HintPath>
+          <HintPath>..\packages\Rx-Core\lib\portable-windows8+net45+wp8\System.Reactive.Core.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -187,15 +143,6 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
-      <ItemGroup>
-        <Reference Include="System.Reactive.Core">
-          <HintPath>..\packages\Rx-Core\lib\portable-windows8+net45+wp8\System.Reactive.Core.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
     <When Condition="($(TargetFrameworkProfile) == 'Profile84') Or ($(TargetFrameworkProfile) == 'Profile111') Or ($(TargetFrameworkProfile) == 'Profile151') Or ($(TargetFrameworkProfile) == 'Profile157') Or ($(TargetFrameworkProfile) == 'Profile259')">
       <ItemGroup>
         <Reference Include="System.Reactive.Core">
@@ -225,6 +172,15 @@
         </Reference>
       </ItemGroup>
     </When>
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
+      <ItemGroup>
+        <Reference Include="System.Reactive.Interfaces">
+          <HintPath>..\packages\Rx-Interfaces\lib\net45\System.Reactive.Interfaces.dll</HintPath>
+          <Private>True</Private>
+          <Paket>True</Paket>
+        </Reference>
+      </ItemGroup>
+    </When>
     <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
       <ItemGroup>
         <Reference Include="System.Reactive.Interfaces">
@@ -252,10 +208,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
       <ItemGroup>
         <Reference Include="System.Reactive.Interfaces">
-          <HintPath>..\packages\Rx-Interfaces\lib\net45\System.Reactive.Interfaces.dll</HintPath>
+          <HintPath>..\packages\Rx-Interfaces\lib\portable-windows8+net45+wp8\System.Reactive.Interfaces.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -279,15 +235,6 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
-      <ItemGroup>
-        <Reference Include="System.Reactive.Interfaces">
-          <HintPath>..\packages\Rx-Interfaces\lib\portable-windows8+net45+wp8\System.Reactive.Interfaces.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
     <When Condition="($(TargetFrameworkProfile) == 'Profile84') Or ($(TargetFrameworkProfile) == 'Profile111') Or ($(TargetFrameworkProfile) == 'Profile151') Or ($(TargetFrameworkProfile) == 'Profile157') Or ($(TargetFrameworkProfile) == 'Profile259')">
       <ItemGroup>
         <Reference Include="System.Reactive.Interfaces">
@@ -317,6 +264,15 @@
         </Reference>
       </ItemGroup>
     </When>
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
+      <ItemGroup>
+        <Reference Include="System.Reactive.Linq">
+          <HintPath>..\packages\Rx-Linq\lib\net45\System.Reactive.Linq.dll</HintPath>
+          <Private>True</Private>
+          <Paket>True</Paket>
+        </Reference>
+      </ItemGroup>
+    </When>
     <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
       <ItemGroup>
         <Reference Include="System.Reactive.Linq">
@@ -344,10 +300,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
       <ItemGroup>
         <Reference Include="System.Reactive.Linq">
-          <HintPath>..\packages\Rx-Linq\lib\net45\System.Reactive.Linq.dll</HintPath>
+          <HintPath>..\packages\Rx-Linq\lib\portable-windows8+net45+wp8\System.Reactive.Linq.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -371,15 +327,6 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
-      <ItemGroup>
-        <Reference Include="System.Reactive.Linq">
-          <HintPath>..\packages\Rx-Linq\lib\portable-windows8+net45+wp8\System.Reactive.Linq.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
     <When Condition="($(TargetFrameworkProfile) == 'Profile84') Or ($(TargetFrameworkProfile) == 'Profile111') Or ($(TargetFrameworkProfile) == 'Profile151') Or ($(TargetFrameworkProfile) == 'Profile157') Or ($(TargetFrameworkProfile) == 'Profile259')">
       <ItemGroup>
         <Reference Include="System.Reactive.Linq">
@@ -409,6 +356,15 @@
         </Reference>
       </ItemGroup>
     </When>
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
+      <ItemGroup>
+        <Reference Include="System.Reactive.PlatformServices">
+          <HintPath>..\packages\Rx-PlatformServices\lib\net45\System.Reactive.PlatformServices.dll</HintPath>
+          <Private>True</Private>
+          <Paket>True</Paket>
+        </Reference>
+      </ItemGroup>
+    </When>
     <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
       <ItemGroup>
         <Reference Include="System.Reactive.PlatformServices">
@@ -436,10 +392,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
       <ItemGroup>
         <Reference Include="System.Reactive.PlatformServices">
-          <HintPath>..\packages\Rx-PlatformServices\lib\net45\System.Reactive.PlatformServices.dll</HintPath>
+          <HintPath>..\packages\Rx-PlatformServices\lib\portable-windows8+net45+wp8\System.Reactive.PlatformServices.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -463,15 +419,6 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
-      <ItemGroup>
-        <Reference Include="System.Reactive.PlatformServices">
-          <HintPath>..\packages\Rx-PlatformServices\lib\portable-windows8+net45+wp8\System.Reactive.PlatformServices.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
     <When Condition="($(TargetFrameworkProfile) == 'Profile84') Or ($(TargetFrameworkProfile) == 'Profile111') Or ($(TargetFrameworkProfile) == 'Profile151') Or ($(TargetFrameworkProfile) == 'Profile157') Or ($(TargetFrameworkProfile) == 'Profile259')">
       <ItemGroup>
         <Reference Include="System.Reactive.PlatformServices">
@@ -513,10 +460,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\packages\Rx-Providers\lib\sl5\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\packages\Rx-Providers\lib\net45\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -528,10 +475,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And $(TargetFrameworkVersion) == 'v7.1'">
+    <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\packages\Rx-Providers\lib\windowsphone71\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\packages\Rx-Providers\lib\sl5\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -543,10 +490,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And ($(TargetFrameworkVersion) == 'v8.0' Or $(TargetFrameworkVersion) == 'v8.1')">
+    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And $(TargetFrameworkVersion) == 'v7.1'">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\packages\Rx-Providers\lib\windowsphone8\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\packages\Rx-Providers\lib\windowsphone71\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -558,10 +505,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And ($(TargetFrameworkVersion) == 'v8.0' Or $(TargetFrameworkVersion) == 'v8.1')">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\packages\Rx-Providers\lib\net45\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\packages\Rx-Providers\lib\windowsphone8\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -573,10 +520,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == 'WindowsPhoneApp') Or ($(TargetFrameworkProfile) == 'Profile32')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\packages\Rx-Providers\lib\portable-win81+wpa81\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\packages\Rx-Providers\lib\portable-windows8+net45+wp8\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -588,10 +535,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile5') Or ($(TargetFrameworkProfile) == 'Profile6') Or ($(TargetFrameworkProfile) == 'Profile14') Or ($(TargetFrameworkProfile) == 'Profile19') Or ($(TargetFrameworkProfile) == 'Profile24') Or ($(TargetFrameworkProfile) == 'Profile37') Or ($(TargetFrameworkProfile) == 'Profile42') Or ($(TargetFrameworkProfile) == 'Profile47') Or ($(TargetFrameworkProfile) == 'Profile147') Or ($(TargetFrameworkProfile) == 'Profile158')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'WindowsPhoneApp') Or ($(TargetFrameworkProfile) == 'Profile32')">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\packages\Rx-Providers\lib\portable-net40+sl5+win8+wp8\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\packages\Rx-Providers\lib\portable-win81+wpa81\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -603,10 +550,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
+    <When Condition="($(TargetFrameworkProfile) == 'Profile5') Or ($(TargetFrameworkProfile) == 'Profile6') Or ($(TargetFrameworkProfile) == 'Profile14') Or ($(TargetFrameworkProfile) == 'Profile19') Or ($(TargetFrameworkProfile) == 'Profile24') Or ($(TargetFrameworkProfile) == 'Profile37') Or ($(TargetFrameworkProfile) == 'Profile42') Or ($(TargetFrameworkProfile) == 'Profile47') Or ($(TargetFrameworkProfile) == 'Profile147') Or ($(TargetFrameworkProfile) == 'Profile158')">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\packages\Rx-Providers\lib\portable-windows8+net45+wp8\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\packages\Rx-Providers\lib\portable-net40+sl5+win8+wp8\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
diff --git a/src/FSharp.Control.Reactive/FSharp.Control.Reactive.fsproj b/src/FSharp.Control.Reactive/FSharp.Control.Reactive.fsproj
index 7532de1..70a75b4 100644
--- a/src/FSharp.Control.Reactive/FSharp.Control.Reactive.fsproj
+++ b/src/FSharp.Control.Reactive/FSharp.Control.Reactive.fsproj
@@ -69,7 +69,16 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETCore') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile44')">
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.0' Or $(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
+      <ItemGroup>
+        <Reference Include="FSharp.Core">
+          <HintPath>..\..\packages\FSharp.Core\lib\net40\FSharp.Core.dll</HintPath>
+          <Private>True</Private>
+          <Paket>True</Paket>
+        </Reference>
+      </ItemGroup>
+    </When>
+    <When Condition="($(TargetFrameworkIdentifier) == '.NETCore') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile44')">
       <ItemGroup>
         <Reference Include="FSharp.Core">
           <HintPath>..\..\packages\FSharp.Core\lib\portable-net45+netcore45\FSharp.Core.dll</HintPath>
@@ -78,10 +87,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.0' Or $(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS')">
       <ItemGroup>
         <Reference Include="FSharp.Core">
-          <HintPath>..\..\packages\FSharp.Core\lib\net40\FSharp.Core.dll</HintPath>
+          <HintPath>..\..\packages\FSharp.Core\lib\portable-net45+monoandroid10+monotouch10+xamarinios10\FSharp.Core.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -134,6 +143,15 @@
         </Reference>
       </ItemGroup>
     </When>
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
+      <ItemGroup>
+        <Reference Include="System.Reactive.Core">
+          <HintPath>..\..\packages\Rx-Core\lib\net45\System.Reactive.Core.dll</HintPath>
+          <Private>True</Private>
+          <Paket>True</Paket>
+        </Reference>
+      </ItemGroup>
+    </When>
     <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
       <ItemGroup>
         <Reference Include="System.Reactive.Core">
@@ -161,10 +179,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
       <ItemGroup>
         <Reference Include="System.Reactive.Core">
-          <HintPath>..\..\packages\Rx-Core\lib\net45\System.Reactive.Core.dll</HintPath>
+          <HintPath>..\..\packages\Rx-Core\lib\portable-windows8+net45+wp8\System.Reactive.Core.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -188,15 +206,6 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
-      <ItemGroup>
-        <Reference Include="System.Reactive.Core">
-          <HintPath>..\..\packages\Rx-Core\lib\portable-windows8+net45+wp8\System.Reactive.Core.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
     <When Condition="($(TargetFrameworkProfile) == 'Profile84') Or ($(TargetFrameworkProfile) == 'Profile111') Or ($(TargetFrameworkProfile) == 'Profile151') Or ($(TargetFrameworkProfile) == 'Profile157') Or ($(TargetFrameworkProfile) == 'Profile259')">
       <ItemGroup>
         <Reference Include="System.Reactive.Core">
@@ -226,6 +235,15 @@
         </Reference>
       </ItemGroup>
     </When>
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
+      <ItemGroup>
+        <Reference Include="System.Reactive.Interfaces">
+          <HintPath>..\..\packages\Rx-Interfaces\lib\net45\System.Reactive.Interfaces.dll</HintPath>
+          <Private>True</Private>
+          <Paket>True</Paket>
+        </Reference>
+      </ItemGroup>
+    </When>
     <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
       <ItemGroup>
         <Reference Include="System.Reactive.Interfaces">
@@ -253,10 +271,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
       <ItemGroup>
         <Reference Include="System.Reactive.Interfaces">
-          <HintPath>..\..\packages\Rx-Interfaces\lib\net45\System.Reactive.Interfaces.dll</HintPath>
+          <HintPath>..\..\packages\Rx-Interfaces\lib\portable-windows8+net45+wp8\System.Reactive.Interfaces.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -280,15 +298,6 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
-      <ItemGroup>
-        <Reference Include="System.Reactive.Interfaces">
-          <HintPath>..\..\packages\Rx-Interfaces\lib\portable-windows8+net45+wp8\System.Reactive.Interfaces.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
     <When Condition="($(TargetFrameworkProfile) == 'Profile84') Or ($(TargetFrameworkProfile) == 'Profile111') Or ($(TargetFrameworkProfile) == 'Profile151') Or ($(TargetFrameworkProfile) == 'Profile157') Or ($(TargetFrameworkProfile) == 'Profile259')">
       <ItemGroup>
         <Reference Include="System.Reactive.Interfaces">
@@ -318,6 +327,15 @@
         </Reference>
       </ItemGroup>
     </When>
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
+      <ItemGroup>
+        <Reference Include="System.Reactive.Linq">
+          <HintPath>..\..\packages\Rx-Linq\lib\net45\System.Reactive.Linq.dll</HintPath>
+          <Private>True</Private>
+          <Paket>True</Paket>
+        </Reference>
+      </ItemGroup>
+    </When>
     <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
       <ItemGroup>
         <Reference Include="System.Reactive.Linq">
@@ -345,10 +363,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
       <ItemGroup>
         <Reference Include="System.Reactive.Linq">
-          <HintPath>..\..\packages\Rx-Linq\lib\net45\System.Reactive.Linq.dll</HintPath>
+          <HintPath>..\..\packages\Rx-Linq\lib\portable-windows8+net45+wp8\System.Reactive.Linq.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -372,15 +390,6 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
-      <ItemGroup>
-        <Reference Include="System.Reactive.Linq">
-          <HintPath>..\..\packages\Rx-Linq\lib\portable-windows8+net45+wp8\System.Reactive.Linq.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
     <When Condition="($(TargetFrameworkProfile) == 'Profile84') Or ($(TargetFrameworkProfile) == 'Profile111') Or ($(TargetFrameworkProfile) == 'Profile151') Or ($(TargetFrameworkProfile) == 'Profile157') Or ($(TargetFrameworkProfile) == 'Profile259')">
       <ItemGroup>
         <Reference Include="System.Reactive.Linq">
@@ -410,6 +419,15 @@
         </Reference>
       </ItemGroup>
     </When>
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
+      <ItemGroup>
+        <Reference Include="System.Reactive.PlatformServices">
+          <HintPath>..\..\packages\Rx-PlatformServices\lib\net45\System.Reactive.PlatformServices.dll</HintPath>
+          <Private>True</Private>
+          <Paket>True</Paket>
+        </Reference>
+      </ItemGroup>
+    </When>
     <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
       <ItemGroup>
         <Reference Include="System.Reactive.PlatformServices">
@@ -437,10 +455,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
       <ItemGroup>
         <Reference Include="System.Reactive.PlatformServices">
-          <HintPath>..\..\packages\Rx-PlatformServices\lib\net45\System.Reactive.PlatformServices.dll</HintPath>
+          <HintPath>..\..\packages\Rx-PlatformServices\lib\portable-windows8+net45+wp8\System.Reactive.PlatformServices.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -464,15 +482,6 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
-      <ItemGroup>
-        <Reference Include="System.Reactive.PlatformServices">
-          <HintPath>..\..\packages\Rx-PlatformServices\lib\portable-windows8+net45+wp8\System.Reactive.PlatformServices.dll</HintPath>
-          <Private>True</Private>
-          <Paket>True</Paket>
-        </Reference>
-      </ItemGroup>
-    </When>
     <When Condition="($(TargetFrameworkProfile) == 'Profile84') Or ($(TargetFrameworkProfile) == 'Profile111') Or ($(TargetFrameworkProfile) == 'Profile151') Or ($(TargetFrameworkProfile) == 'Profile157') Or ($(TargetFrameworkProfile) == 'Profile259')">
       <ItemGroup>
         <Reference Include="System.Reactive.PlatformServices">
@@ -514,10 +523,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\..\packages\Rx-Providers\lib\sl5\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\..\packages\Rx-Providers\lib\net45\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -529,10 +538,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And $(TargetFrameworkVersion) == 'v7.1'">
+    <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\..\packages\Rx-Providers\lib\windowsphone71\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\..\packages\Rx-Providers\lib\sl5\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -544,10 +553,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And ($(TargetFrameworkVersion) == 'v8.0' Or $(TargetFrameworkVersion) == 'v8.1')">
+    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And $(TargetFrameworkVersion) == 'v7.1'">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\..\packages\Rx-Providers\lib\windowsphone8\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\..\packages\Rx-Providers\lib\windowsphone71\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -559,10 +568,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And ($(TargetFrameworkVersion) == 'v8.0' Or $(TargetFrameworkVersion) == 'v8.1')">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\..\packages\Rx-Providers\lib\net45\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\..\packages\Rx-Providers\lib\windowsphone8\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -574,10 +583,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == 'WindowsPhoneApp') Or ($(TargetFrameworkProfile) == 'Profile32')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\..\packages\Rx-Providers\lib\portable-win81+wpa81\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\..\packages\Rx-Providers\lib\portable-windows8+net45+wp8\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -589,10 +598,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile5') Or ($(TargetFrameworkProfile) == 'Profile6') Or ($(TargetFrameworkProfile) == 'Profile14') Or ($(TargetFrameworkProfile) == 'Profile19') Or ($(TargetFrameworkProfile) == 'Profile24') Or ($(TargetFrameworkProfile) == 'Profile37') Or ($(TargetFrameworkProfile) == 'Profile42') Or ($(TargetFrameworkProfile) == 'Profile47') Or ($(TargetFrameworkProfile) == 'Profile147') Or ($(TargetFrameworkProfile) == 'Profile158')">
+    <When Condition="($(TargetFrameworkIdentifier) == 'WindowsPhoneApp') Or ($(TargetFrameworkProfile) == 'Profile32')">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\..\packages\Rx-Providers\lib\portable-net40+sl5+win8+wp8\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\..\packages\Rx-Providers\lib\portable-win81+wpa81\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
@@ -604,10 +613,10 @@
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
+    <When Condition="($(TargetFrameworkProfile) == 'Profile5') Or ($(TargetFrameworkProfile) == 'Profile6') Or ($(TargetFrameworkProfile) == 'Profile14') Or ($(TargetFrameworkProfile) == 'Profile19') Or ($(TargetFrameworkProfile) == 'Profile24') Or ($(TargetFrameworkProfile) == 'Profile37') Or ($(TargetFrameworkProfile) == 'Profile42') Or ($(TargetFrameworkProfile) == 'Profile47') Or ($(TargetFrameworkProfile) == 'Profile147') Or ($(TargetFrameworkProfile) == 'Profile158')">
       <ItemGroup>
         <Reference Include="System.Reactive.Providers">
-          <HintPath>..\..\packages\Rx-Providers\lib\portable-windows8+net45+wp8\System.Reactive.Providers.dll</HintPath>
+          <HintPath>..\..\packages\Rx-Providers\lib\portable-net40+sl5+win8+wp8\System.Reactive.Providers.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
diff --git a/src/Observable.fs b/src/Observable.fs
index b29927c..4687628 100644
--- a/src/Observable.fs
+++ b/src/Observable.fs
@@ -560,7 +560,7 @@ module Observable =
     /// Filters the observable elements of a sequence based on a predicate by 
     /// incorporating the element's index
     let filteri predicate (source: IObservable<'T>)  = 
-        Observable.Where( source, Func<_,_> predicate )
+        Observable.Where( source, Func<_,_,_> (fun i x -> predicate x i) )
 
 
     /// Invokes a specified action after the source observable sequence
@@ -1028,12 +1028,7 @@ module Observable =
     /// Maps the given observable with the given function and the 
     /// index of the element
     let mapi (f:int -> 'Source -> 'Result) (source:IObservable<'Source>) =
-        source
-        |> Observable.scan ( fun (i,_) x -> (i+1,Some(x))) (-1,None)
-        |> Observable.map
-            (   function
-                | i, Some(x) -> f i x
-                | _, None    -> invalidOp "Invalid state"   )
+        Observable.Select (source, Func<_,_,_> (fun i x -> f x i))
 
 
     /// Maps two observables to the specified function.
diff --git a/tests/FSharp.Control.Reactive.Tests.fsproj b/tests/FSharp.Control.Reactive.Tests.fsproj
index da9c547..53ec695 100644
--- a/tests/FSharp.Control.Reactive.Tests.fsproj
+++ b/tests/FSharp.Control.Reactive.Tests.fsproj
@@ -9,7 +9,7 @@
     <OutputType>Library</OutputType>
     <RootNamespace>FSharp.Control.Reactive.Tests</RootNamespace>
     <AssemblyName>FSharp.Control.Reactive.Tests</AssemblyName>
-    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.5.2</TargetFrameworkVersion>
     <Name>FSharp.Control.Reactive.Tests</Name>
     <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\</SolutionDir>
     <TargetFrameworkProfile />
@@ -49,11 +49,23 @@
   </Choose>
   <Import Project="$(FSharpTargetsPath)" Condition="Exists('$(FSharpTargetsPath)')" />
   <ItemGroup>
+    <Compile Include="FsCheckAddin.fs">
+      <Paket>True</Paket>
+    </Compile>
     <Compile Include="ObservableSpecs.fs" />
     <None Include="paket.references" />
   </ItemGroup>
   <ItemGroup>
+    <Reference Include="FSharp.Core, Version=4.4.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
+      <Private>True</Private>
+    </Reference>
     <Reference Include="mscorlib" />
+    <Reference Include="nunit.core">
+      <HintPath>..\packages\NUnit.Runners\tools\lib\nunit.core.dll</HintPath>
+    </Reference>
+    <Reference Include="nunit.core.interfaces">
+      <HintPath>..\packages\NUnit.Runners\tools\lib\nunit.core.interfaces.dll</HintPath>
+    </Reference>
     <Reference Include="System.Numerics" />
   </ItemGroup>
   <ItemGroup>
@@ -66,55 +78,53 @@
   <Import Project="$(SolutionDir)\.nuget\NuGet.targets" Condition="Exists('$(SolutionDir)\.nuget\NuGet.targets')" />
   <Import Project="$(SolutionDir)\.paket\paket.targets" />
   <Choose>
-    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v2.0' Or $(TargetFrameworkVersion) == 'v3.0' Or $(TargetFrameworkVersion) == 'v3.5')">
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
       <ItemGroup>
-        <Reference Include="FSharp.Core">
-          <HintPath>..\packages\FSharp.Core\lib\net20\FSharp.Core.dll</HintPath>
+        <Reference Include="FsCheck">
+          <HintPath>..\packages\FsCheck\lib\net45\FsCheck.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETCore') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile44')">
+    <When Condition="($(TargetFrameworkIdentifier) == '.NETCore') Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile44')">
       <ItemGroup>
-        <Reference Include="FSharp.Core">
-          <HintPath>..\packages\FSharp.Core\lib\portable-net45+netcore45\FSharp.Core.dll</HintPath>
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@@ -147,6 +157,15 @@
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+          <Paket>True</Paket>
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@@ -239,6 +249,15 @@
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+          <Private>True</Private>
+          <Paket>True</Paket>
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         <Reference Include="System.Reactive.Experimental">
@@ -331,6 +341,15 @@
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+          <Private>True</Private>
+          <Paket>True</Paket>
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+    </When>
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@@ -358,10 +377,10 @@
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         <Reference Include="System.Reactive.Interfaces">
@@ -423,6 +433,15 @@
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+        <Reference Include="System.Reactive.Linq">
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+          <Private>True</Private>
+          <Paket>True</Paket>
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+    </When>
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+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
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         <Reference Include="System.Reactive.Linq">
-          <HintPath>..\packages\Rx-Linq\lib\net45\System.Reactive.Linq.dll</HintPath>
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         <Reference Include="System.Reactive.Linq">
@@ -515,6 +525,15 @@
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+          <Private>True</Private>
+          <Paket>True</Paket>
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+    <When Condition="($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch') Or ($(TargetFrameworkIdentifier) == 'Xamarin.iOS') Or ($(TargetFrameworkIdentifier) == 'Xamarin.Mac') Or ($(TargetFrameworkProfile) == 'Profile7') Or ($(TargetFrameworkProfile) == 'Profile31') Or ($(TargetFrameworkProfile) == 'Profile44') Or ($(TargetFrameworkProfile) == 'Profile49') Or ($(TargetFrameworkProfile) == 'Profile78')">
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-          <HintPath>..\packages\Rx-PlatformServices\lib\net45\System.Reactive.PlatformServices.dll</HintPath>
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@@ -679,10 +689,10 @@
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-    <When Condition="($(TargetFrameworkIdentifier) == 'WindowsPhoneApp') Or ($(TargetFrameworkProfile) == 'Profile32')">
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         <Reference Include="System.Reactive.Providers">
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       </ItemGroup>
     </When>
-    <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
+    <When Condition="$(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1')">
       <ItemGroup>
         <Reference Include="Microsoft.Reactive.Testing">
-          <HintPath>..\packages\Rx-Testing\lib\sl5\Microsoft.Reactive.Testing.dll</HintPath>
+          <HintPath>..\packages\Rx-Testing\lib\net45\Microsoft.Reactive.Testing.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
-        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTesting.Silverlight">
+        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework">
           <Paket>True</Paket>
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And $(TargetFrameworkVersion) == 'v7.1'">
+    <When Condition="$(TargetFrameworkIdentifier) == 'Silverlight' And $(TargetFrameworkVersion) == 'v5.0'">
       <ItemGroup>
         <Reference Include="Microsoft.Reactive.Testing">
-          <HintPath>..\packages\Rx-Testing\lib\windowsphone71\Microsoft.Reactive.Testing.dll</HintPath>
+          <HintPath>..\packages\Rx-Testing\lib\sl5\Microsoft.Reactive.Testing.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
+        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTesting.Silverlight">
+          <Paket>True</Paket>
+        </Reference>
       </ItemGroup>
     </When>
-    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And ($(TargetFrameworkVersion) == 'v8.0' Or $(TargetFrameworkVersion) == 'v8.1')">
+    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And $(TargetFrameworkVersion) == 'v7.1'">
       <ItemGroup>
         <Reference Include="Microsoft.Reactive.Testing">
-          <HintPath>..\packages\Rx-Testing\lib\windowsphone8\Microsoft.Reactive.Testing.dll</HintPath>
+          <HintPath>..\packages\Rx-Testing\lib\windowsphone71\Microsoft.Reactive.Testing.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
       </ItemGroup>
     </When>
-    <When Condition="($(TargetFrameworkIdentifier) == '.NETFramework' And ($(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6')) Or ($(TargetFrameworkIdentifier) == 'MonoAndroid') Or ($(TargetFrameworkIdentifier) == 'MonoTouch')">
+    <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And ($(TargetFrameworkVersion) == 'v8.0' Or $(TargetFrameworkVersion) == 'v8.1')">
       <ItemGroup>
         <Reference Include="Microsoft.Reactive.Testing">
-          <HintPath>..\packages\Rx-Testing\lib\net45\Microsoft.Reactive.Testing.dll</HintPath>
+          <HintPath>..\packages\Rx-Testing\lib\windowsphone8\Microsoft.Reactive.Testing.dll</HintPath>
           <Private>True</Private>
           <Paket>True</Paket>
         </Reference>
-        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework">
-          <Paket>True</Paket>
-        </Reference>
       </ItemGroup>
     </When>
   </Choose>
diff --git a/tests/FsCheckAddin.fs b/tests/FsCheckAddin.fs
new file mode 100644
index 0000000..3a349a6
--- /dev/null
+++ b/tests/FsCheckAddin.fs
@@ -0,0 +1,15 @@
+namespace FsCheck.NUnit.Examples
+
+open NUnit.Core.Extensibility
+
+open FsCheck.NUnit
+open FsCheck.NUnit.Addin
+
+[<NUnitAddin(Description = "FsCheck addin")>]
+type FsCheckAddin() =
+    interface IAddin with
+        override x.Install host =
+            let tcBuilder = new FsCheckTestCaseBuilder()
+            host.GetExtensionPoint("TestCaseBuilders").Install(tcBuilder)
+            true
+
diff --git a/tests/ObservableSpecs.fs b/tests/ObservableSpecs.fs
index a889f4a..1ebabf0 100644
--- a/tests/ObservableSpecs.fs
+++ b/tests/ObservableSpecs.fs
@@ -5,6 +5,7 @@ open System.Reactive.Linq
 open FSharp.Control.Reactive
 open Builders
 open NUnit.Framework
+open FsCheck.NUnit
 open Microsoft.Reactive.Testing
 open System.Reactive.Subjects
 open System.Reactive.Concurrency
@@ -550,4 +551,34 @@ let ``FlatMapAsync should take F# async workflows and flatmap them to observable
     Assert.That(result.Count, Is.EqualTo 3)
     Assert.That(result.[0], Is.EqualTo expected)
     Assert.That(result.[1], Is.EqualTo expected)
-    Assert.That(result.[2], Is.EqualTo expected)
\ No newline at end of file
+    Assert.That(result.[2], Is.EqualTo expected)
+
+[<Property>]
+let ``Observable.mapi should be equivalent to Array.mapi`` (items : int array) =
+    items
+    |> Observable.ofSeq
+    |> Observable.mapi (fun i x -> (i, x))
+    |> Observable.toEnumerable
+    |> Seq.toArray
+    |> (=) (items |> Array.mapi (fun i x -> (i, x)))
+
+[<Property>]
+let ``filteri should be equivalent to mapi then filter`` (items : int array) =
+    let predicate i x = (i % 2 = 0) && (x > 0)
+
+    let filtered =
+        items
+        |> Observable.ofSeq
+        |> Observable.mapi (fun i x -> (i, x))
+        |> Observable.filter (fun (i, x) -> predicate i x)
+        |> Observable.map snd
+        |> Observable.toEnumerable
+        |> Seq.toArray
+
+    let filtered' =
+        Observable.ofSeq items
+        |> Observable.filteri predicate
+        |> Observable.toEnumerable
+        |> Seq.toArray
+    
+    filtered = filtered'
\ No newline at end of file
diff --git a/tests/paket.references b/tests/paket.references
index 9e1763c..163f51b 100644
--- a/tests/paket.references
+++ b/tests/paket.references
@@ -1,6 +1,7 @@
 FSharp.Core
 NUnit
 NUnit.Runners
+FsCheck.NUnit
 Rx-Core
 Rx-Experimental
 Rx-Interfaces