diff --git a/dblayer.php b/dblayer.php
index 550108e..ea9731a 100644
--- a/dblayer.php
+++ b/dblayer.php
@@ -393,7 +393,7 @@ class dblayer
     $dataOK = array ();
     foreach ($this->fields as $field=>$desc)
     {
-      if (isset ($data[$field]))
+      if (array_key_exists ($field, $data))
         $dataOK[$field] = $data[$field];
     }
 
@@ -841,7 +841,7 @@ class dblayer
     }
     foreach ($this->fields as $field=>$desc)
     {
-      if (isset ($data[$field]))
+      if (array_key_exists ($field, $data))
         $dataOK[$field] = $data[$field];
     }