diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -2729,7 +2729,7 @@
     ('u', 'user', None, _('list the author (long with -v)')),
     ('d', 'date', None, _('list the date (short with -q)')),
     ] + formatteropts + walkopts,
-    _('[OPTION]... PATTERN [FILE]...'),
+    _('--diff [OPTION] ... PATTERN [FILE]...'),
     helpcategory=command.CATEGORY_FILE_CONTENTS,
     inferrepo=True,
     intents={INTENT_READONLY})