diff --git a/src/ngircd/defines.h b/src/ngircd/defines.h
index 4bcb6aff..b894dbc7 100644
--- a/src/ngircd/defines.h
+++ b/src/ngircd/defines.h
@@ -1,6 +1,6 @@
 /*
  * ngIRCd -- The Next Generation IRC Daemon
- * Copyright (c)2001-2010 Alexander Barton (alex@barton.de)
+ * Copyright (c)2001-2012 Alexander Barton (alex@barton.de)
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -32,6 +32,9 @@
 #define MAX_WHOWAS 64			/* Max. number of WHOWAS items */
 #define DEFAULT_WHOWAS 5		/* default count for WHOWAS command */
 
+#define MAX_CMODES_ARG 5		/* Max. number of channel modes with
+					 * arguments per MODE command */
+
 #define CONNECTION_POOL 100		/* Size of default connection pool */
 
 #define CLIENT_ID_LEN 64		/* Max. length of an IRC ID; see RFC
diff --git a/src/ngircd/irc-mode.c b/src/ngircd/irc-mode.c
index 01f87621..9afe9078 100644
--- a/src/ngircd/irc-mode.c
+++ b/src/ngircd/irc-mode.c
@@ -375,7 +375,7 @@ Channel_Mode(CLIENT *Client, REQUEST *Req, CLIENT *Origin, CHANNEL *Channel)
 	char the_modes[COMMAND_LEN], the_args[COMMAND_LEN], x[2],
 	    argadd[CLIENT_PASS_LEN], *mode_ptr;
 	bool connected, set, skiponce, retval, onchannel, modeok, use_servermode;
-	int mode_arg, arg_arg;
+	int mode_arg, arg_arg, mode_arg_count = 0;
 	CLIENT *client;
 	long l;
 	size_t len;
@@ -491,6 +491,8 @@ Channel_Mode(CLIENT *Client, REQUEST *Req, CLIENT *Origin, CHANNEL *Channel)
 					Client_ID(Origin), Channel_Name(Channel));
 			break;
 		case 'k': /* Channel key */
+			if (mode_arg_count++ >= MAX_CMODES_ARG)
+				break;
 			if (!set) {
 				if (modeok)
 					x[0] = *mode_ptr;
@@ -525,6 +527,8 @@ Channel_Mode(CLIENT *Client, REQUEST *Req, CLIENT *Origin, CHANNEL *Channel)
 			}
 			break;
 		case 'l': /* Member limit */
+			if (mode_arg_count++ >= MAX_CMODES_ARG)
+				break;
 			if (!set) {
 				if (modeok)
 					x[0] = *mode_ptr;
@@ -635,6 +639,8 @@ Channel_Mode(CLIENT *Client, REQUEST *Req, CLIENT *Origin, CHANNEL *Channel)
 		/* --- Channel lists --- */
 		case 'I': /* Invite lists */
 		case 'b': /* Ban lists */
+			if (mode_arg_count++ >= MAX_CMODES_ARG)
+				break;
 			if (arg_arg > mode_arg) {
 				/* modify list */
 				if (modeok) {