diff --git a/src/foundation.cs b/src/foundation.cs
index bdf4a20c..deab1ddb 100644
--- a/src/foundation.cs
+++ b/src/foundation.cs
@@ -4540,7 +4540,7 @@ interface NSJsonSerialization {
 
 		[Static]
 		[Export ("JSONObjectWithData:options:error:")]
-		NSObject Deserialize (NSData data, NSJsonReadingOptions opt, NSError error);
+		NSObject Deserialize (NSData data, NSJsonReadingOptions opt, out NSError error);
 
 		[Static]
 		[Export ("writeJSONObject:toStream:options:error:")]