diff --git a/mercurial/help.py b/mercurial/help.py
index cf1e15f91c90ec894c283caf6e7b562ccdc73c98_bWVyY3VyaWFsL2hlbHAucHk=..98bfce9bd5e53e88d1c94af5f24b0e91795e18a3_bWVyY3VyaWFsL2hlbHAucHk= 100644
--- a/mercurial/help.py
+++ b/mercurial/help.py
@@ -214,7 +214,8 @@
       _('Specifying Revisions'), loaddoc('revisions')),
     (['filesets', 'fileset'], _("Specifying File Sets"), loaddoc('filesets')),
     (['diffs'], _('Diff Formats'), loaddoc('diffs')),
-    (['merge-tools', 'mergetools'], _('Merge Tools'), loaddoc('merge-tools')),
+    (['merge-tools', 'mergetools', 'mergetool'], _('Merge Tools'),
+     loaddoc('merge-tools')),
     (['templating', 'templates', 'template', 'style'], _('Template Usage'),
      loaddoc('templates')),
     (['urls'], _('URL Paths'), loaddoc('urls')),