diff --git a/src/messageui.cs b/src/messageui.cs
index abea001b87..d6ea09332f 100644
--- a/src/messageui.cs
+++ b/src/messageui.cs
@@ -71,7 +71,7 @@ namespace MessageUI {
 	
 	[BaseType (typeof (UINavigationController))]
 	interface MFMessageComposeViewController : UIAppearance {
-		[Export ("messageComposeDelegate", ArgumentSemantic.Assign), NullAllowed]
+		[Export ("messageComposeDelegate", ArgumentSemantic.Weak), NullAllowed]
 		NSObject WeakMessageComposeDelegate { get; set; }
 		
 		[Wrap ("WeakMessageComposeDelegate")]