diff --git a/ChangeLog b/ChangeLog
index 534af1ff8..13354b84f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2013-01-31  Doug Simons <doug.simons@testplant.com>
+
+    * Source/NSindow.m: Don't unregister delegate notifications if same delegate is set twice.
+
 2013-02-21  Frank Le Grand <frank.legrand@testplant.com>
     Prelimirary/basic implementation of NSCollectionView and NSCollectionViewItem.
 	This is a work in progress.
diff --git a/Source/NSWindow.m b/Source/NSWindow.m
index 09b45aa0c..6779d7e36 100644
--- a/Source/NSWindow.m
+++ b/Source/NSWindow.m
@@ -5320,6 +5320,9 @@ current key view.<br />
 */
 - (void) setDelegate: (id)anObject
 {
+  if (anObject == _delegate)
+    return; // don't remove previously registered notifications if delegate is unchanged!
+  
   if (_delegate)
     {
       [nc removeObserver: _delegate name: nil object: self];