--- a/hgext/bookmarks.py	Mon Nov 22 17:57:11 2010 +0100
+++ b/hgext/bookmarks.py	Mon Nov 22 18:15:58 2010 +0100
@@ -137,7 +137,7 @@
         write(repo)
         return
 
-    if mark != None:
+    if mark is not None:
         if "\n" in mark:
             raise util.Abort(_("bookmark name cannot contain newlines"))
         mark = mark.strip()