--- a/mercurial/commands.py	Tue Apr 19 15:19:54 2011 +0200
+++ b/mercurial/commands.py	Tue Apr 19 14:56:46 2011 +0300
@@ -4198,7 +4198,7 @@
             raise util.Abort(_("uncommitted local changes"))
 
     if date:
-        if rev:
+        if rev is not None:
             raise util.Abort(_("you can't specify a revision and a date"))
         rev = cmdutil.finddate(ui, repo, date)