diff --git a/src/irc/irc-commands.c b/src/irc/irc-commands.c
index 2c01f8405..e973d5628 100644
--- a/src/irc/irc-commands.c
+++ b/src/irc/irc-commands.c
@@ -96,7 +96,7 @@ t_irc_command irc_commands[] =
     N_("channel[,channel] [key[,key]]"),
     N_("channel: channel name to join\n"
        "    key: key to join the channel"),
-    NULL, 1, MAX_ARGS, 0, 1, NULL, irc_send_cmd_join, irc_recv_cmd_join },
+    "%C", 1, MAX_ARGS, 0, 1, NULL, irc_send_cmd_join, irc_recv_cmd_join },
   { "kick", N_("forcibly remove a user from a channel"),
     N_("[channel] nickname [comment]"),
     N_(" channel: channel where user is\n"
diff --git a/weechat/src/irc/irc-commands.c b/weechat/src/irc/irc-commands.c
index 2c01f8405..e973d5628 100644
--- a/weechat/src/irc/irc-commands.c
+++ b/weechat/src/irc/irc-commands.c
@@ -96,7 +96,7 @@ t_irc_command irc_commands[] =
     N_("channel[,channel] [key[,key]]"),
     N_("channel: channel name to join\n"
        "    key: key to join the channel"),
-    NULL, 1, MAX_ARGS, 0, 1, NULL, irc_send_cmd_join, irc_recv_cmd_join },
+    "%C", 1, MAX_ARGS, 0, 1, NULL, irc_send_cmd_join, irc_recv_cmd_join },
   { "kick", N_("forcibly remove a user from a channel"),
     N_("[channel] nickname [comment]"),
     N_(" channel: channel where user is\n"