diff --git a/csharp/src/Google.Protobuf/ExtensionRegistry.cs b/csharp/src/Google.Protobuf/ExtensionRegistry.cs
index 8056304c788d..06701d515251 100644
--- a/csharp/src/Google.Protobuf/ExtensionRegistry.cs
+++ b/csharp/src/Google.Protobuf/ExtensionRegistry.cs
@@ -85,11 +85,11 @@ public void Add(Extension extension)
         /// <summary>
         /// Adds the specified extensions to the reigstry
         /// </summary>
-        public void Add(IEnumerable<Extension> newExtensions)
+        public void AddRange(IEnumerable<Extension> extensions)
         {
-            ProtoPreconditions.CheckNotNull(newExtensions, nameof(newExtensions));
+            ProtoPreconditions.CheckNotNull(extensions, nameof(extensions));
 
-            foreach (var extension in newExtensions)
+            foreach (var extension in extensions)
                 Add(extension);
         }
 
diff --git a/csharp/src/Google.Protobuf/Reflection/FileDescriptor.cs b/csharp/src/Google.Protobuf/Reflection/FileDescriptor.cs
index 4c2fe54d560b..9b20e3d22ad6 100644
--- a/csharp/src/Google.Protobuf/Reflection/FileDescriptor.cs
+++ b/csharp/src/Google.Protobuf/Reflection/FileDescriptor.cs
@@ -407,7 +407,7 @@ public static FileDescriptor FromGeneratedCode(
 
         private static void AddAllExtensions(FileDescriptor[] dependencies, GeneratedClrTypeInfo generatedInfo, ExtensionRegistry registry)
         {
-            registry.Add(dependencies.SelectMany(GetAllDependedExtensions).Concat(GetAllGeneratedExtensions(generatedInfo)).ToArray());
+            registry.AddRange(dependencies.SelectMany(GetAllDependedExtensions).Concat(GetAllGeneratedExtensions(generatedInfo)).ToArray());
         }
 
         private static IEnumerable<Extension> GetAllGeneratedExtensions(GeneratedClrTypeInfo generated)