diff --git a/ChangeLog.adoc b/ChangeLog.adoc
index 2477ac12c..a638dbd15 100644
--- a/ChangeLog.adoc
+++ b/ChangeLog.adoc
@@ -30,6 +30,7 @@ Bug fixes::
 
   * core: flush stdout/stderr before forking in hook_process function (issue #1441)
   * core: fix evaluation of condition with nested "if" (issue #1434)
+  * irc: fix crash when receiving a malformed message 324 (channel mode)
   * irc: add nick changes in the hotlist (except self nick change)
   * irc: case-insensitive comparison on incoming CTCP command, force upper case on CTCP replies (issue #1439)
   * irc: fix memory leak when the channel topic is changed
diff --git a/src/plugins/irc/irc-mode.c b/src/plugins/irc/irc-mode.c
index 2237a344b..e79f0deb7 100644
--- a/src/plugins/irc/irc-mode.c
+++ b/src/plugins/irc/irc-mode.c
@@ -224,17 +224,20 @@ irc_mode_channel_update (struct t_irc_server *server,
                     current_arg++;
                 if (pos[0] == chanmode)
                 {
-                    chanmode_found = 1;
-                    if (set_flag == '+')
+                    if (!chanmode_found)
                     {
-                        str_mode[0] = pos[0];
-                        str_mode[1] = '\0';
-                        strcat (new_modes, str_mode);
-                        if (argument)
+                        chanmode_found = 1;
+                        if (set_flag == '+')
                         {
-                            if (new_args[0])
-                                strcat (new_args, " ");
-                            strcat (new_args, argument);
+                            str_mode[0] = pos[0];
+                            str_mode[1] = '\0';
+                            strcat (new_modes, str_mode);
+                            if (argument)
+                            {
+                                if (new_args[0])
+                                    strcat (new_args, " ");
+                                strcat (new_args, argument);
+                            }
                         }
                     }
                 }