diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -2710,10 +2710,10 @@
 )
 
 @command('grep',
-    [('0', 'print0', None, _('end fields with NUL')),
+    [('', 'diff', None, _('print all revisions when the term was introduced '
+                          'or removed')),
+    ('0', 'print0', None, _('end fields with NUL')),
     ('', 'all', None, _('print all revisions that match (DEPRECATED) ')),
-    ('', 'diff', None, _('print all revisions when the term was introduced '
-                         'or removed')),
     ('a', 'text', None, _('treat all files as text')),
     ('f', 'follow', None,
      _('follow changeset history,'
diff --git a/tests/test-completion.t b/tests/test-completion.t
--- a/tests/test-completion.t
+++ b/tests/test-completion.t
@@ -326,7 +326,7 @@
   files: rev, print0, include, exclude, template, subrepos
   forget: interactive, include, exclude, dry-run
   graft: rev, base, continue, stop, abort, edit, log, no-commit, force, currentdate, currentuser, date, user, tool, dry-run
-  grep: print0, all, diff, text, follow, ignore-case, files-with-matches, line-number, rev, all-files, user, date, template, include, exclude
+  grep: diff, print0, all, text, follow, ignore-case, files-with-matches, line-number, rev, all-files, user, date, template, include, exclude
   heads: rev, topo, active, closed, style, template
   help: extension, command, keyword, system
   identify: rev, num, id, branch, tags, bookmarks, ssh, remotecmd, insecure, template