diff --git a/roagen.php b/roagen.php
index 99d3a75..429681a 100755
--- a/roagen.php
+++ b/roagen.php
@@ -109,7 +109,7 @@ foreach($files as $file)
                     $ta = 'NULL';
                 }*/
                 $roas['roas'][$i]['maxLength'] = $mask;
-                $roas['roas'][$i]['ta'] = $ta;
+                $roas['roas'][$i]['ta'] = (empty($ta) ? NULL : $ta);
                 $i++;
             }
         }
@@ -188,7 +188,7 @@ foreach($files as $file)
                     $ta = 'NULL';
                 }*/
                 $roas['roas'][$i]['maxLength'] = $mask;
-                $roas['roas'][$i]['ta'] = $ta;
+                $roas['roas'][$i]['ta'] = (empty($ta) ? NULL : $ta);
                 $i++;
             }
         }