diff --git a/mercurial/help.py b/mercurial/help.py
--- a/mercurial/help.py
+++ b/mercurial/help.py
@@ -143,6 +143,8 @@ def topicmatch(ui, kw):
                     cmddoc = gettext(entry[0].__doc__).splitlines()[0]
                 else:
                     cmddoc = _('(no help text available)')
+                if filtercmd(ui, cmdname, kw, cmddoc):
+                    continue
                 results['extensioncommands'].append((cmdname, cmddoc))
     return results
 
diff --git a/tests/test-help.t b/tests/test-help.t
--- a/tests/test-help.t
+++ b/tests/test-help.t
@@ -1213,7 +1213,7 @@ Test -e / -c / -k combinations
   Commands:
   $ hg help -e|egrep '^[A-Z].*:|^ debug'
   Extensions:
-  $ hg help -k|egrep '^[A-Z].*:'
+  $ hg help -k|egrep '^[A-Z].*:|^ debug'
   Topics:
   Commands:
   Extensions: