diff --git a/src/ObjCRuntime/Runtime.cs b/src/ObjCRuntime/Runtime.cs
index f58d2b04b9..3606e27f88 100644
--- a/src/ObjCRuntime/Runtime.cs
+++ b/src/ObjCRuntime/Runtime.cs
@@ -855,7 +855,6 @@ namespace ObjCRuntime {
 #endif
 		static Delegate CreateBlockProxy (MethodInfo method, IntPtr block)
 		{
-			NSObject.DangerousRetain (block);
 			return (Delegate) method.Invoke (null, new object [] { block } );
 		}
 
diff --git a/tests/bindings-test/ApiDefinition.cs b/tests/bindings-test/ApiDefinition.cs
index e92457191c..4c99638094 100644
--- a/tests/bindings-test/ApiDefinition.cs
+++ b/tests/bindings-test/ApiDefinition.cs
@@ -284,6 +284,13 @@ namespace Bindings.Test {
 
 		[Export ("callOptionalCallback")]
 		void CallOptionalCallback ();
+
+		[Export ("testFreedBlocks")]
+		void TestFreedBlocks ();
+
+		[Static]
+		[Export ("freedBlockCount")]
+		int FreedBlockCount { get; }
 	}
 }
 
diff --git a/tests/bindings-test/RegistrarBindingTest.cs b/tests/bindings-test/RegistrarBindingTest.cs
index 495de89ac3..dc2441da23 100644
--- a/tests/bindings-test/RegistrarBindingTest.cs
+++ b/tests/bindings-test/RegistrarBindingTest.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Threading;
 
 #if __UNIFIED__
 using Foundation;
@@ -63,7 +64,7 @@ namespace Xamarin.BindingTests
 			}
 		}
 
-		class BlockCallbackTester : ObjCBlockTester
+		public class BlockCallbackTester : ObjCBlockTester
 		{
 			public override void ClassCallback (Action<int> completionHandler)
 			{
diff --git a/tests/bindings-test/bindings-test-mac.csproj b/tests/bindings-test/bindings-test-mac.csproj
index f950c3b6ef..4e89ea09d8 100644
--- a/tests/bindings-test/bindings-test-mac.csproj
+++ b/tests/bindings-test/bindings-test-mac.csproj
@@ -62,6 +62,7 @@
     <Compile Include="..\api-shared\ObjCRuntime\Registrar.cs">
       <Link>Registrar.cs</Link>
     </Compile>
+    <Compile Include="RegistrarBindingTest.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="..\..\tests\test-libraries\libtest.m">
diff --git a/tests/monotouch-test/ObjCRuntime/RegistrarTest.cs b/tests/monotouch-test/ObjCRuntime/RegistrarTest.cs
index 75c1e1f378..a8cb32f9ae 100644
--- a/tests/monotouch-test/ObjCRuntime/RegistrarTest.cs
+++ b/tests/monotouch-test/ObjCRuntime/RegistrarTest.cs
@@ -2026,6 +2026,30 @@ namespace MonoTouchFixtures.ObjCRuntime {
 			}
 		}
 
+		[Test]
+		public void BlockCollection ()
+		{
+			Exception ex = null;
+			int initialFreedCount = ObjCBlockTester.FreedBlockCount;
+			var thread = new Thread (() => {
+				try {
+					using (var obj = new Xamarin.BindingTests.RegistrarBindingTest.BlockCallbackTester ()) {
+						for (int i = 0; i < 10000; i++)
+							obj.TestFreedBlocks ();
+					}
+				} catch (Exception e) {
+					ex = e;
+				}
+			});
+			thread.Start ();
+			thread.Join ();
+			GC.Collect ();
+			GC.WaitForPendingFinalizers ();
+			TestRuntime.RunAsync (DateTime.Now.AddSeconds (30), () => { }, () => ObjCBlockTester.FreedBlockCount > initialFreedCount);
+			Assert.IsNull (ex, "No exceptions");
+			Assert.That (ObjCBlockTester.FreedBlockCount, Is.GreaterThan (initialFreedCount), "freed blocks");
+		}
+
 		[Test]
 		public void TestCtors ()
 		{
diff --git a/tests/test-libraries/libtest.h b/tests/test-libraries/libtest.h
index a9998bd2ba..9d86bb10aa 100644
--- a/tests/test-libraries/libtest.h
+++ b/tests/test-libraries/libtest.h
@@ -1,5 +1,6 @@
 #import <Foundation/Foundation.h>
 #include <simd/simd.h>
+#include <libkern/OSAtomic.h>
 
 #include "rename.h"
 
@@ -149,6 +150,14 @@ typedef unsigned int (^RegistrarTestBlock) (unsigned int magic);
 -(void) callClassCallback;
 -(void) callRequiredCallback;
 -(void) callOptionalCallback;
+
+-(void) testFreedBlocks;
++(int) freedBlockCount;
+@end
+
+@interface FreedNotifier : NSObject {
+}
+-(void) dealloc;
 @end
 
 #ifdef __cplusplus
diff --git a/tests/test-libraries/libtest.m b/tests/test-libraries/libtest.m
index ca6a7da5e0..5a8a4375a1 100644
--- a/tests/test-libraries/libtest.m
+++ b/tests/test-libraries/libtest.m
@@ -510,6 +510,8 @@ static UltimateMachine *shared;
 }
 @end
 
+static volatile int freed_blocks = 0;
+
 @implementation ObjCBlockTester
 -(void) classCallback: (void (^)(int32_t magic_number))completionHandler
 {
@@ -549,6 +551,30 @@ static UltimateMachine *shared;
 	assert (called);
 }
 
+-(void) testFreedBlocks
+{
+	FreedNotifier* obj = [[FreedNotifier alloc] init];
+	__block bool success = false;
+	[self classCallback: ^(int magic_number)
+	{
+		assert (magic_number == 42);
+		success = obj != NULL; // this captures the 'obj', and it's only freed when the block is freed.
+	}];
+	assert (success);
+	[obj release];
+}
++(int) freedBlockCount
+{
+	return freed_blocks;
+}
+@end
+
+@implementation FreedNotifier
+-(void) dealloc
+{
+	OSAtomicIncrement32 (&freed_blocks);
+	[super dealloc];
+}
 @end
 
 #include "libtest.decompile.m"
diff --git a/tests/test-libraries/rename.h b/tests/test-libraries/rename.h
index d11719d189..47f6f40490 100644
--- a/tests/test-libraries/rename.h
+++ b/tests/test-libraries/rename.h
@@ -4,6 +4,7 @@
 	#define useZLib           object_useZLib
 	#define ObjCRegistrarTest object_ObjCRegistrarTest
 	#define ObjCBlockTester   object_ObjCBlockTester
+	#define FreedNotifier     object_FreedNotifier
 	#define FakeType2         object_FakeType2
 	#define UltimateMachine   object_UltimateMachine
 	#define FrameworkTest     object_FrameworkTest
@@ -67,6 +68,7 @@
 	#define useZLib           ar_useZLib
 	#define ObjCRegistrarTest ar_ObjCRegistrarTest
 	#define ObjCBlockTester   ar_ObjCBlockTester
+	#define FreedNotifier     ar_FreedNotifier
 	#define FakeType2         ar_FakeType2
 	#define UltimateMachine   ar_UltimateMachine
 	#define FrameworkTest     ar_FrameworkTest