diff --git a/AppKit/CPWindow/CPWindow.j b/AppKit/CPWindow/CPWindow.j
index 82ced5e49..4066e28f5 100644
--- a/AppKit/CPWindow/CPWindow.j
+++ b/AppKit/CPWindow/CPWindow.j
@@ -3524,7 +3524,7 @@ var keyViewComparator = function(lhs, rhs, context)
 
     // If not, check to see if the delegate has one.
     if ([self _delegateRespondsToWindowWillUndoManager])
-        return [self _sendDelegateWindowWillReturnUndoManager:self];
+        return [self _sendDelegateWindowWillReturnUndoManager];
 
     // If not, create one.
     if (!_undoManager)