diff --git a/Source/NSKeyValueObserving.m b/Source/NSKeyValueObserving.m
index 28e37a71f..79cbe1b17 100644
--- a/Source/NSKeyValueObserving.m
+++ b/Source/NSKeyValueObserving.m
@@ -1322,8 +1322,8 @@ replacementForClass(Class c)
   info = (GSKVOInfo *)[self observationInfo];
   if (info != nil)
     {
-      id            old;
-      NSDictionary  *change;
+      id                        old;
+      NSMutableDictionary       *change;
 
       change = [NSMutableDictionary dictionary];
       old = [self valueForKey: aKey];