diff --git a/lib/filestorage/file_storage.php b/lib/filestorage/file_storage.php
index 32fec854601..0e92edfe87a 100644
--- a/lib/filestorage/file_storage.php
+++ b/lib/filestorage/file_storage.php
@@ -1721,6 +1721,8 @@ class file_storage {
      * @return array (contenthash, filesize, newfile)
      */
     public function add_string_to_pool($content) {
+        global $CFG;
+
         $contenthash = sha1($content);
         $filesize = strlen($content); // binary length
 
@@ -1755,7 +1757,13 @@ class file_storage {
         // Hopefully this works around most potential race conditions.
 
         $prev = ignore_user_abort(true);
-        $newsize = file_put_contents($hashfile.'.tmp', $content, LOCK_EX);
+
+        if (!empty($CFG->preventfilelocking)) {
+            $newsize = file_put_contents($hashfile.'.tmp', $content);
+        } else {
+            $newsize = file_put_contents($hashfile.'.tmp', $content, LOCK_EX);
+        }
+
         if ($newsize === false) {
             // Borked permissions most likely.
             ignore_user_abort($prev);