--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -54,7 +54,8 @@ class localrepository(object):
     def hook(self, name, throw=False, **args):
         def runhook(name, cmd):
             self.ui.note(_("running hook %s: %s\n") % (name, cmd))
-            env = dict([('HG_' + k.upper(), v) for k, v in args.iteritems()])
+            env = dict([('HG_' + k.upper(), v) for k, v in args.iteritems()] +
+                       [(k.upper(), v) for k, v in args.iteritems()])
             r = util.system(cmd, environ=env, cwd=self.root)
             if r:
                 desc, r = util.explain_exit(r)