diff --git a/course/mod.php b/course/mod.php
index 5df2b31d206..b912844d7ef 100644
--- a/course/mod.php
+++ b/course/mod.php
@@ -3,7 +3,7 @@
 //  Moves, adds, updates, duplicates or deletes modules in a course
 
     require("../config.php");
-    require("lib.php");
+    require_once("lib.php");
 
     require_login();