diff --git a/lib/datalib.php b/lib/datalib.php
index e10b4564844..520c6216cb9 100644
--- a/lib/datalib.php
+++ b/lib/datalib.php
@@ -2603,6 +2603,10 @@ function update_timezone_records($timezones) {
 function get_course_mods($courseid) {
     global $CFG;
 
+    if (empty($courseid)) {
+        return false; // avoid warnings
+    }
+
     return get_records_sql("SELECT cm.*, m.name as modname
                             FROM {$CFG->prefix}modules m,
                                  {$CFG->prefix}course_modules cm