diff --git a/libraries/pmd_common.php b/libraries/pmd_common.php
index 7829bf74ec..739481d0f1 100644
--- a/libraries/pmd_common.php
+++ b/libraries/pmd_common.php
@@ -312,7 +312,7 @@ function PMA_deletePage($pg)
 {
     $cfgRelation = PMA_getRelationsParam();
     if (! $cfgRelation['pdfwork']) {
-        return null;
+        return false;
     }
 
     $query = "DELETE FROM " . PMA_Util::backquote($cfgRelation['db'])