diff --git a/mod/chat/gui_header_js/jsupdate.php b/mod/chat/gui_header_js/jsupdate.php
index 726a14b2b7c..29e42ef601b 100644
--- a/mod/chat/gui_header_js/jsupdate.php
+++ b/mod/chat/gui_header_js/jsupdate.php
@@ -17,7 +17,7 @@
 define('NO_MOODLE_COOKIES', true); // Session not used here.
 
 require('../../../config.php');
-require('../lib.php');
+require_once('../lib.php');
 
 $chatsid      = required_param('chat_sid', PARAM_ALPHANUM);
 $chatlasttime = optional_param('chat_lasttime', 0, PARAM_INT);
diff --git a/mod/chat/gui_header_js/jsupdated.php b/mod/chat/gui_header_js/jsupdated.php
index 3e564c673c9..68426784ac1 100644
--- a/mod/chat/gui_header_js/jsupdated.php
+++ b/mod/chat/gui_header_js/jsupdated.php
@@ -34,7 +34,7 @@ define('NO_MOODLE_COOKIES', true); // Session not used here.
 define('NO_OUTPUT_BUFFERING', true);
 
 require('../../../config.php');
-require('../lib.php');
+require_once('../lib.php');
 
 // We are going to run for a long time.
 // Avoid being terminated by php.
diff --git a/mod/chat/gui_sockets/chatinput.php b/mod/chat/gui_sockets/chatinput.php
index 0bfd9c062f7..799731e2f52 100644
--- a/mod/chat/gui_sockets/chatinput.php
+++ b/mod/chat/gui_sockets/chatinput.php
@@ -17,7 +17,7 @@
 define('NO_MOODLE_COOKIES', true); // Session not used here.
 
 require('../../../config.php');
-require('../lib.php');
+require_once('../lib.php');
 
 $chatsid = required_param('chat_sid', PARAM_ALPHANUM);