diff --git a/admin/tool/customlang/locallib.php b/admin/tool/customlang/locallib.php
index 02ae558dcb8..83e879a866d 100644
--- a/admin/tool/customlang/locallib.php
+++ b/admin/tool/customlang/locallib.php
@@ -159,6 +159,11 @@ class tool_customlang_utils {
                         $needsupdate = true;
                         $current[$stringid]->local          = $stringlocal;
                         $current[$stringid]->timecustomized = $now;
+                    } else if (isset($currentlocal) && $stringlocal !== $currentlocal) {
+                        // If local string has been removed, we need to remove also the old local value from DB.
+                        $needsupdate = true;
+                        $current[$stringid]->local          = null;
+                        $current[$stringid]->timecustomized = $now;
                     }
 
                     if ($needsupdate) {