diff --git a/libraries/pmd_common.php b/libraries/pmd_common.php
index f451fbc85f..a9e825dd67 100644
--- a/libraries/pmd_common.php
+++ b/libraries/pmd_common.php
@@ -756,5 +756,5 @@ function PMA_saveDesignerSetting($index, $value)
         }
     }
 
-    return $success;
+    return (bool) $success;
 }