diff --git a/phpBB/includes/db/driver/driver.php b/phpBB/includes/db/driver/driver.php
index 39211a5af4..9692ee71b9 100644
--- a/phpBB/includes/db/driver/driver.php
+++ b/phpBB/includes/db/driver/driver.php
@@ -82,7 +82,7 @@ class phpbb_db_driver
 
         // Fill default sql layer based on the class being called.
         // This can be changed by the specified layer itself later if needed.
-        $this->sql_layer = substr(get_class($this), 5);
+        $this->sql_layer = substr(get_class($this), strlen('phpbb_db_driver_'));
 
         // Do not change this please! This variable is used to easy the use of it - and is hardcoded.
         $this->any_char = chr(0) . '%';