diff --git a/src/Foundation/NSMutableDictionary.cs b/src/Foundation/NSMutableDictionary.cs
index 596dbd82..fda4b9f2 100644
--- a/src/Foundation/NSMutableDictionary.cs
+++ b/src/Foundation/NSMutableDictionary.cs
@@ -171,7 +171,7 @@ IDictionaryEnumerator IDictionary.GetEnumerator ()
 		}
 
 		[Serializable]
-		class ShimEnumerator : IDictionaryEnumerator, IEnumerator {
+		class ShimEnumerator : IDictionaryEnumerator, IDisposable, IEnumerator {
 			IEnumerator<KeyValuePair<NSObject, NSObject>> e;
 
 			public ShimEnumerator (NSMutableDictionary host)