diff --git a/README.md b/README.md
index f085bb1759..b44ec6f2ba 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,7 @@
   - [Param](#param)
 - [Describing Methods](#describing-methods)
 - [Parameters](#parameters)
+  - [Params Class](#params-class)
   - [Declared](#declared)
   - [Include Missing](#include-missing)
 - [Parameter Validation and Coercion](#parameter-validation-and-coercion)
@@ -501,9 +502,19 @@ Route string parameters will have precedence.
 
 By default parameters are available as `ActiveSupport::HashWithIndifferentAccess`. This can be changed to, for example, Ruby `Hash` or `Hashie::Mash` for the entire API.
 
-[TODO]
+```ruby
+class API < Grape::API
+  include Grape::Extensions::Hashie::Mash::ParamBuilder
+
+  params do
+    optional :color, type: String
+  end
+  get do
+    params.color # instead of params[:color]
+  end
+```
 
-The class can be overridden on individual parameter blocks using `build_with` as follows.
+The class can also be overridden on individual parameter blocks using `build_with` as follows.
 
 ```ruby
 params do
@@ -514,6 +525,8 @@ end
 
 In the example above, `params["color"]` will return `nil` since `params` is a plain `Hash`.
 
+Available parameter builders are `Grape::Extensions::Hash::ParamBuilder`, `Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder` and `Grape::Extensions::Hashie::Mash::ParamBuilder`.
+
 ### Declared
 
 Grape allows you to access only the parameters that have been declared by your `params` block. It filters out the params that have been passed, but are not allowed. Consider the following API endpoint:
@@ -526,7 +539,7 @@ post 'users/signup' do
 end
 ````
 
-If we do not specify any params, `declared` will return an empty `ActiveSupport::HashWithIndifferentAccess` hash.
+If you do not specify any parameters, `declared` will return an empty hash.
 
 **Request**
 
@@ -543,8 +556,8 @@ curl -X POST -H "Content-Type: application/json" localhost:9292/users/signup -d
 
 ````
 
-Once we add parameters requirements, grape will start returning only the declared params[:
-]
+Once we add parameters requirements, grape will start returning only the declared parameters.
+
 ````ruby
 format :json
 
@@ -579,7 +592,7 @@ curl -X POST -H "Content-Type: application/json" localhost:9292/users/signup -d
 }
 ````
 
-The returned hash is a `ActiveSupport::HashWithIndifferentAccess` hash.
+The returned hash is an `ActiveSupport::HashWithIndifferentAccess`.
 
 The `#declared` method is not available to `before` filters, as those are evaluated prior to parameter coercion.
 
diff --git a/UPGRADING.md b/UPGRADING.md
index 1a481f60e8..165e03443a 100644
--- a/UPGRADING.md
+++ b/UPGRADING.md
@@ -5,9 +5,33 @@ Upgrading Grape
 
 #### Changes in Parameter Class
 
-The default class for `params` has changed from `Hashie::Mash` to `ActiveSupport::HashWithIndifferentAccess` and the `hashie` dependency has been removed. To restore the behavior of prior versions, add `hashie` to your `Gemfile` and use `TODO`.
+The default class for `params` has changed from `Hashie::Mash` to `ActiveSupport::HashWithIndifferentAccess` and the `hashie` dependency has been removed. This means that by default you can no longer access parameters by method name.
 
-[TODO]
+```
+class API < Grape::API
+  params do
+    optional :color, type: String
+  end
+  get do
+    params[:color] # use params[:color] instead of params.color
+  end
+end
+```
+
+To restore the behavior of prior versions, add `hashie` to your `Gemfile` and `include Grape::Extensions::Hashie::Mash::ParamBuilder` in your API.
+
+```
+class API < Grape::API
+  include Grape::Extensions::Hashie::Mash::ParamBuilder
+
+  params do
+    optional :color, type: String
+  end
+  get do
+    # params.color works
+  end
+end
+```
 
 This behavior can also be overridden on individual parameter blocks using `build_with`.
 
@@ -26,7 +50,7 @@ def request
 end
 ```
 
-See [#1594](https://github.com/ruby-grape/grape/pull/1594) for more information.
+See [#1610](https://github.com/ruby-grape/grape/pull/1610) for more information.
 
 ### Upgrading to >= 0.19.1
 
diff --git a/lib/grape.rb b/lib/grape.rb
index e3f3ddd1c4..e5e9e7636f 100644
--- a/lib/grape.rb
+++ b/lib/grape.rb
@@ -26,7 +26,7 @@
 I18n.load_path << File.expand_path('../grape/locale/en.yml', __FILE__)
 
 module Grape
-  extend ActiveSupport::Autoload
+  extend ::ActiveSupport::Autoload
 
   eager_autoload do
     autoload :API
@@ -47,14 +47,14 @@ module Grape
   end
 
   module Http
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
     eager_autoload do
       autoload :Headers
     end
   end
 
   module Exceptions
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
     autoload :Base
     autoload :Validation
     autoload :ValidationArrayErrors
@@ -78,22 +78,27 @@ module Exceptions
   end
 
   module Extensions
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
 
     autoload :DeepMergeableHash
     autoload :DeepSymbolizeHash
     autoload :Hash
-    autoload :HashWithIndifferentAccess
+
+    module ActiveSupport
+      extend ::ActiveSupport::Autoload
+
+      autoload :HashWithIndifferentAccess
+    end
 
     module Hashie
-      extend ActiveSupport::Autoload
+      extend ::ActiveSupport::Autoload
 
       autoload :Mash
     end
   end
 
   module Middleware
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
     autoload :Base
     autoload :Versioner
     autoload :Formatter
@@ -102,7 +107,7 @@ module Middleware
     autoload :Stack
 
     module Auth
-      extend ActiveSupport::Autoload
+      extend ::ActiveSupport::Autoload
       autoload :Base
       autoload :DSL
       autoload :StrategyInfo
@@ -110,7 +115,7 @@ module Auth
     end
 
     module Versioner
-      extend ActiveSupport::Autoload
+      extend ::ActiveSupport::Autoload
       autoload :Path
       autoload :Header
       autoload :Param
@@ -119,7 +124,7 @@ module Versioner
   end
 
   module Util
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
     autoload :InheritableValues
     autoload :StackableValues
     autoload :ReverseStackableValues
@@ -129,7 +134,7 @@ module Util
   end
 
   module ErrorFormatter
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
     autoload :Base
     autoload :Json
     autoload :Txt
@@ -137,7 +142,7 @@ module ErrorFormatter
   end
 
   module Formatter
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
     autoload :Json
     autoload :SerializableHash
     autoload :Txt
@@ -145,13 +150,13 @@ module Formatter
   end
 
   module Parser
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
     autoload :Json
     autoload :Xml
   end
 
   module DSL
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
     eager_autoload do
       autoload :API
       autoload :Callbacks
@@ -170,17 +175,17 @@ module DSL
   end
 
   class API
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
     autoload :Helpers
   end
 
   module Presenters
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
     autoload :Presenter
   end
 
   module ServeFile
-    extend ActiveSupport::Autoload
+    extend ::ActiveSupport::Autoload
     autoload :FileResponse
     autoload :FileBody
     autoload :SendfileResponse
diff --git a/lib/grape/dsl/parameters.rb b/lib/grape/dsl/parameters.rb
index 44eb99a9fb..2f427ad4fb 100644
--- a/lib/grape/dsl/parameters.rb
+++ b/lib/grape/dsl/parameters.rb
@@ -11,8 +11,9 @@ module Parameters
       # Set the module used to build the request.params.
       #
       # @param build_with the ParamBuilder module to use when building request.params
-      #   Available builders are;
-      #     * Grape::Extensions::HashWithIndifferentAccess::ParamBuilder (default)
+      #   Available builders are:
+      #
+      #     * Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder (default)
       #     * Grape::Extensions::Hash::ParamBuilder
       #     * Grape::Extensions::Hashie::Mash::ParamBuilder
       #
@@ -30,7 +31,7 @@ module Parameters
       #       end
       #     end
       def build_with(build_with = nil)
-        @api.namespace_inheritable(:build_with, build_with)
+        @api.namespace_inheritable(:build_params_with, build_with)
       end
 
       # Include reusable params rules among current.
diff --git a/lib/grape/endpoint.rb b/lib/grape/endpoint.rb
index 523dbdfde2..3ff2d6c380 100644
--- a/lib/grape/endpoint.rb
+++ b/lib/grape/endpoint.rb
@@ -237,7 +237,7 @@ def equals?(e)
     def run
       ActiveSupport::Notifications.instrument('endpoint_run.grape', endpoint: self, env: env) do
         @header = {}
-        @request = Grape::Request.new(env, build_params_with: namespace_inheritable(:build_with))
+        @request = Grape::Request.new(env, build_params_with: namespace_inheritable(:build_params_with))
         @params = @request.params
         @headers = @request.headers
 
diff --git a/lib/grape/extensions/active_support/hash_with_indifferent_access.rb b/lib/grape/extensions/active_support/hash_with_indifferent_access.rb
new file mode 100644
index 0000000000..291e34decd
--- /dev/null
+++ b/lib/grape/extensions/active_support/hash_with_indifferent_access.rb
@@ -0,0 +1,25 @@
+module Grape
+  module Extensions
+    module ActiveSupport
+      module HashWithIndifferentAccess
+        extend ::ActiveSupport::Concern
+
+        included do
+          namespace_inheritable(:build_params_with, Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder)
+        end
+
+        def params_builder
+          Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder
+        end
+
+        module ParamBuilder
+          def build_params
+            params = ::ActiveSupport::HashWithIndifferentAccess[rack_params]
+            params.deep_merge!(grape_routing_args) if env[Grape::Env::GRAPE_ROUTING_ARGS]
+            params
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/grape/extensions/hash.rb b/lib/grape/extensions/hash.rb
index 9785fd68c8..77d0757630 100644
--- a/lib/grape/extensions/hash.rb
+++ b/lib/grape/extensions/hash.rb
@@ -2,6 +2,12 @@ module Grape
   module Extensions
     module Hash
       module ParamBuilder
+        extend ::ActiveSupport::Concern
+
+        included do
+          namespace_inheritable(:build_params_with, Grape::Extensions::Hash::ParamBuilder)
+        end
+
         def build_params
           params = Grape::Extensions::DeepMergeableHash[rack_params]
           params.deep_merge!(grape_routing_args) if env[Grape::Env::GRAPE_ROUTING_ARGS]
diff --git a/lib/grape/extensions/hash_with_indifferent_access.rb b/lib/grape/extensions/hash_with_indifferent_access.rb
deleted file mode 100644
index 14608a0ef1..0000000000
--- a/lib/grape/extensions/hash_with_indifferent_access.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-module Grape
-  module Extensions
-    module HashWithIndifferentAccess
-      def params_builder
-        Grape::Extensions::HashWithIndifferentAccess::ParamBuilder
-      end
-
-      module ParamBuilder
-        def build_params
-          params = ActiveSupport::HashWithIndifferentAccess[rack_params]
-          params.deep_merge!(grape_routing_args) if env[Grape::Env::GRAPE_ROUTING_ARGS]
-          params
-        end
-      end
-    end
-  end
-end
diff --git a/lib/grape/extensions/hashie/mash.rb b/lib/grape/extensions/hashie/mash.rb
index e60677bfce..50958f3224 100644
--- a/lib/grape/extensions/hashie/mash.rb
+++ b/lib/grape/extensions/hashie/mash.rb
@@ -2,11 +2,17 @@ module Grape
   module Extensions
     module Hashie
       module Mash
-        def params_builder
-          Grape::Extensions::Hashie::Mash::ParamBuilder
-        end
-
         module ParamBuilder
+          extend ::ActiveSupport::Concern
+
+          included do
+            namespace_inheritable(:build_params_with, Grape::Extensions::Hashie::Mash::ParamBuilder)
+          end
+
+          def params_builder
+            Grape::Extensions::Hashie::Mash::ParamBuilder
+          end
+
           def build_params
             params = ::Hashie::Mash.new(rack_params)
             params.deep_merge!(grape_routing_args) if env[Grape::Env::GRAPE_ROUTING_ARGS]
diff --git a/lib/grape/request.rb b/lib/grape/request.rb
index deef61c454..0f11dff9e6 100644
--- a/lib/grape/request.rb
+++ b/lib/grape/request.rb
@@ -5,7 +5,7 @@ class Request < Rack::Request
     alias rack_params params
 
     def initialize(env, options = {})
-      extend options[:build_params_with] || Grape::Extensions::HashWithIndifferentAccess::ParamBuilder
+      extend options[:build_params_with] || Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder
       super(env)
     end
 
diff --git a/lib/grape/validations/types/custom_type_coercer.rb b/lib/grape/validations/types/custom_type_coercer.rb
index a67bd1db73..da28474eb0 100644
--- a/lib/grape/validations/types/custom_type_coercer.rb
+++ b/lib/grape/validations/types/custom_type_coercer.rb
@@ -147,7 +147,7 @@ def infer_type_check(type)
         # Enforce symbolized keys for complex types
         # by wrapping the coercion method such that
         # any Hash objects in the immediate heirarchy
-        # have their keys recursively symbolized
+        # have their keys recursively symbolized.
         # This helps common libs such as JSON to work easily.
         #
         # @param type see #new
diff --git a/lib/grape/validations/validators/coerce.rb b/lib/grape/validations/validators/coerce.rb
index b93834fe85..76db19d47c 100644
--- a/lib/grape/validations/validators/coerce.rb
+++ b/lib/grape/validations/validators/coerce.rb
@@ -11,7 +11,6 @@ def initialize(*_args)
       end
 
       def validate(request)
-        @request = request
         super
       end
 
@@ -19,7 +18,7 @@ def validate_param!(attr_name, params)
         raise Grape::Exceptions::Validation, params: [@scope.full_name(attr_name)], message: message(:coerce) unless params.is_a? Hash
         new_value = coerce_value(params[attr_name])
         raise Grape::Exceptions::Validation, params: [@scope.full_name(attr_name)], message: message(:coerce) unless valid_type?(new_value)
-        params[attr_name] = @request.respond_to?(:post_process_params) ? @request.post_process_params(new_value) : new_value
+        params[attr_name] = new_value
       end
 
       private
@@ -38,6 +37,7 @@ def valid_type?(val)
 
         # Allow nil, to ignore when a parameter is absent
         return true if val.nil?
+
         converter.value_coerced? val
       end
 
diff --git a/spec/grape/endpoint_spec.rb b/spec/grape/endpoint_spec.rb
index 270923ca73..1af9b73b94 100644
--- a/spec/grape/endpoint_spec.rb
+++ b/spec/grape/endpoint_spec.rb
@@ -250,88 +250,6 @@ def app
   end
 
   describe '#params' do
-    context 'build params with Hash' do
-      it 'should be Hash' do
-        subject.params do
-          build_with Grape::Extensions::Hash::ParamBuilder
-        end
-
-        subject.get '/foo' do
-          params.class
-        end
-
-        get '/foo'
-        expect(last_response.status).to eq(200)
-        expect(last_response.body).to eq('Hash')
-      end
-    end
-
-    context 'build params with HashWithIndifferentAccess' do
-      it 'should be ActiveSupport::HashWithIndifferentAccess' do
-        subject.params do
-          build_with Grape::Extensions::HashWithIndifferentAccess::ParamBuilder
-        end
-
-        subject.get '/foo' do
-          params.class
-        end
-
-        get '/foo'
-        expect(last_response.status).to eq(200)
-        expect(last_response.body).to eq('ActiveSupport::HashWithIndifferentAccess')
-      end
-
-      it 'parse sub hash params' do
-        subject.params do
-          build_with Grape::Extensions::HashWithIndifferentAccess::ParamBuilder
-
-          optional :a, type: Hash do
-            optional :b, type: Hash do
-              optional :c, type: String
-            end
-            optional :d, type: Array
-          end
-        end
-        subject.get '/foo' do
-          [params[:a]['b'][:c], params['a'][:d]]
-        end
-
-        get '/foo', a: { b: { c: 'bar' }, d: ['foo'] }
-        expect(last_response.status).to eq(200)
-        expect(last_response.body).to eq('["bar", ["foo"]]')
-      end
-    end
-
-    context 'build params with Hashie::Mash' do
-      it 'should be Hashie::Mash' do
-        subject.params do
-          build_with Grape::Extensions::Hashie::Mash::ParamBuilder
-        end
-
-        subject.get '/foo' do
-          params.class
-        end
-
-        get '/foo'
-        expect(last_response.status).to eq(200)
-        expect(last_response.body).to eq('Hashie::Mash')
-      end
-
-      it 'is indifferent to key or symbol access' do
-        subject.params do
-          build_with Grape::Extensions::Hashie::Mash::ParamBuilder
-          requires :a, type: String
-        end
-        subject.get '/foo' do
-          [params[:a], params['a']]
-        end
-
-        get '/foo', a: 'bar'
-        expect(last_response.status).to eq(200)
-        expect(last_response.body).to eq('["bar", "bar"]')
-      end
-    end
-
     context 'default class' do
       it 'should be a ActiveSupport::HashWithIndifferentAccess' do
         subject.get '/foo' do
@@ -1024,79 +942,6 @@ def app
       end
     end
 
-    context 'params presented as a plain Ruby Hash' do
-      it 'symbolizes params keys' do
-        subject.params do
-          optional :a, type: Hash do
-            optional :b, type: Hash do
-              optional :c, type: String
-            end
-            optional :d, type: Array
-          end
-        end
-
-        subject.get '/foo' do
-          [params[:a][:b][:c], params[:a][:d]]
-        end
-
-        get '/foo', 'a' => { b: { c: 'bar' }, 'd' => ['foo'] }
-        expect(last_response.status).to eq(200)
-        expect(last_response.body).to eq('["bar", ["foo"]]')
-      end
-
-      it 'symbolizes the params' do
-        subject.params do
-          build_with Grape::Extensions::Hash::ParamBuilder
-          requires :a, type: String
-        end
-
-        subject.get '/foo' do
-          [params[:a], params['a']]
-        end
-
-        get '/foo', a: 'bar'
-        expect(last_response.status).to eq(200)
-        expect(last_response.body).to eq('["bar", nil]')
-      end
-    end
-
-    context 'params presented as a HashWithIndifferentAccess' do
-      it 'params are indifferent to symbol or string keys' do
-        subject.params do
-          build_with Grape::Extensions::HashWithIndifferentAccess::ParamBuilder
-          optional :a, type: Hash do
-            optional :b, type: Hash do
-              optional :c, type: String
-            end
-            optional :d, type: Array
-          end
-        end
-
-        subject.get '/foo' do
-          [params[:a]['b'][:c], params['a'][:d]]
-        end
-
-        get '/foo', 'a' => { b: { c: 'bar' }, 'd' => ['foo'] }
-        expect(last_response.status).to eq(200)
-        expect(last_response.body).to eq('["bar", ["foo"]]')
-      end
-
-      it 'responds to string keys' do
-        subject.params do
-          build_with Grape::Extensions::HashWithIndifferentAccess::ParamBuilder
-          requires :a, type: String
-        end
-
-        subject.get '/foo' do
-          [params[:a], params['a']]
-        end
-
-        get '/foo', a: 'bar'
-        expect(last_response.status).to eq(200)
-        expect(last_response.body).to eq('["bar", "bar"]')
-      end
-    end
-
     context 'sets a value to params' do
       it 'params' do
         subject.params do
diff --git a/spec/grape/extensions/param_builders/hash_spec.rb b/spec/grape/extensions/param_builders/hash_spec.rb
new file mode 100644
index 0000000000..27371fd983
--- /dev/null
+++ b/spec/grape/extensions/param_builders/hash_spec.rb
@@ -0,0 +1,83 @@
+require 'spec_helper'
+
+describe Grape::Extensions::Hash::ParamBuilder do
+  subject { Class.new(Grape::API) }
+
+  def app
+    subject
+  end
+
+  describe 'in an endpoint' do
+    context '#params' do
+      before do
+        subject.params do
+          build_with Grape::Extensions::Hash::ParamBuilder
+        end
+
+        subject.get do
+          params.class
+        end
+      end
+
+      it 'should be of type Hash' do
+        get '/'
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('Hash')
+      end
+    end
+  end
+
+  describe 'in an api' do
+    before do
+      subject.send(:include, Grape::Extensions::Hash::ParamBuilder)
+    end
+
+    context '#params' do
+      before do
+        subject.get do
+          params.class
+        end
+      end
+
+      it 'should be Hash' do
+        get '/'
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('Hash')
+      end
+    end
+
+    it 'symbolizes params keys' do
+      subject.params do
+        optional :a, type: Hash do
+          optional :b, type: Hash do
+            optional :c, type: String
+          end
+          optional :d, type: Array
+        end
+      end
+
+      subject.get '/foo' do
+        [params[:a][:b][:c], params[:a][:d]]
+      end
+
+      get '/foo', 'a' => { b: { c: 'bar' }, 'd' => ['foo'] }
+      expect(last_response.status).to eq(200)
+      expect(last_response.body).to eq('["bar", ["foo"]]')
+    end
+
+    it 'symbolizes the params' do
+      subject.params do
+        build_with Grape::Extensions::Hash::ParamBuilder
+        requires :a, type: String
+      end
+
+      subject.get '/foo' do
+        [params[:a], params['a']]
+      end
+
+      get '/foo', a: 'bar'
+      expect(last_response.status).to eq(200)
+      expect(last_response.body).to eq('["bar", nil]')
+    end
+  end
+end
diff --git a/spec/grape/extensions/param_builders/hash_with_indifferent_access_spec.rb b/spec/grape/extensions/param_builders/hash_with_indifferent_access_spec.rb
new file mode 100644
index 0000000000..1c2ea2c4f9
--- /dev/null
+++ b/spec/grape/extensions/param_builders/hash_with_indifferent_access_spec.rb
@@ -0,0 +1,105 @@
+require 'spec_helper'
+
+describe Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder do
+  subject { Class.new(Grape::API) }
+
+  def app
+    subject
+  end
+
+  describe 'in an endpoint' do
+    context '#params' do
+      before do
+        subject.params do
+          build_with Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder
+        end
+
+        subject.get do
+          params.class
+        end
+      end
+
+      it 'should be of type Hash' do
+        get '/'
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('ActiveSupport::HashWithIndifferentAccess')
+      end
+    end
+  end
+
+  describe 'in an api' do
+    before do
+      subject.send(:include, Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder)
+    end
+
+    context '#params' do
+      before do
+        subject.get do
+          params.class
+        end
+      end
+
+      it 'is a Hash' do
+        get '/'
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('ActiveSupport::HashWithIndifferentAccess')
+      end
+
+      it 'parses sub hash params' do
+        subject.params do
+          build_with Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder
+
+          optional :a, type: Hash do
+            optional :b, type: Hash do
+              optional :c, type: String
+            end
+            optional :d, type: Array
+          end
+        end
+
+        subject.get '/foo' do
+          [params[:a]['b'][:c], params['a'][:d]]
+        end
+
+        get '/foo', a: { b: { c: 'bar' }, d: ['foo'] }
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('["bar", ["foo"]]')
+      end
+
+      it 'params are indifferent to symbol or string keys' do
+        subject.params do
+          build_with Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder
+          optional :a, type: Hash do
+            optional :b, type: Hash do
+              optional :c, type: String
+            end
+            optional :d, type: Array
+          end
+        end
+
+        subject.get '/foo' do
+          [params[:a]['b'][:c], params['a'][:d]]
+        end
+
+        get '/foo', 'a' => { b: { c: 'bar' }, 'd' => ['foo'] }
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('["bar", ["foo"]]')
+      end
+
+      it 'responds to string keys' do
+        subject.params do
+          build_with Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder
+          requires :a, type: String
+        end
+
+        subject.get '/foo' do
+          [params[:a], params['a']]
+        end
+
+        get '/foo', a: 'bar'
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('["bar", "bar"]')
+      end
+    end
+  end
+end
diff --git a/spec/grape/extensions/param_builders/hashie/mash_spec.rb b/spec/grape/extensions/param_builders/hashie/mash_spec.rb
new file mode 100644
index 0000000000..0a5975f2d5
--- /dev/null
+++ b/spec/grape/extensions/param_builders/hashie/mash_spec.rb
@@ -0,0 +1,79 @@
+require 'spec_helper'
+
+describe Grape::Extensions::Hashie::Mash::ParamBuilder do
+  subject { Class.new(Grape::API) }
+
+  def app
+    subject
+  end
+
+  describe 'in an endpoint' do
+    context '#params' do
+      before do
+        subject.params do
+          build_with Grape::Extensions::Hashie::Mash::ParamBuilder
+        end
+
+        subject.get do
+          params.class
+        end
+      end
+
+      it 'should be of type Hashie::Mash' do
+        get '/'
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('Hashie::Mash')
+      end
+    end
+  end
+
+  describe 'in an api' do
+    before do
+      subject.send(:include, Grape::Extensions::Hashie::Mash::ParamBuilder)
+    end
+
+    context '#params' do
+      before do
+        subject.get do
+          params.class
+        end
+      end
+
+      it 'should be Hashie::Mash' do
+        get '/'
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('Hashie::Mash')
+      end
+    end
+
+    context 'in a nested namespace api' do
+      before do
+        subject.namespace :foo do
+          get do
+            params.class
+          end
+        end
+      end
+
+      it 'should be Hashie::Mash' do
+        get '/foo'
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('Hashie::Mash')
+      end
+    end
+
+    it 'is indifferent to key or symbol access' do
+      subject.params do
+        build_with Grape::Extensions::Hashie::Mash::ParamBuilder
+        requires :a, type: String
+      end
+      subject.get '/foo' do
+        [params[:a], params['a']]
+      end
+
+      get '/foo', a: 'bar'
+      expect(last_response.status).to eq(200)
+      expect(last_response.body).to eq('["bar", "bar"]')
+    end
+  end
+end