diff --git a/Source/NSOutlineView.m b/Source/NSOutlineView.m
index 956101da1..f9b69ce1e 100644
--- a/Source/NSOutlineView.m
+++ b/Source/NSOutlineView.m
@@ -1327,7 +1327,7 @@ static int _levelForItem(NSOutlineView *outline,
 	item = nil;
       else
 	item = [self itemAtRow: i];
-      
+
       childIndex = j;
 
 
@@ -1341,5 +1341,13 @@ static int _levelForItem(NSOutlineView *outline,
     return NO;
 }
 
+- (BOOL) prepareForDragOperation: (id<NSDraggingInfo>)sender
+{
+  [self setNeedsDisplayInRect: oldDraggingRect];
+  [self displayIfNeeded];
+
+  return YES;
+}
+
 @end /* implementation of NSOutlineView */