diff --git a/application/forms.class.inc.php b/application/forms.class.inc.php
index deab25a2d..60d3f88c9 100644
--- a/application/forms.class.inc.php
+++ b/application/forms.class.inc.php
@@ -883,7 +883,7 @@ class DesignerTextField extends DesignerFormField
 	{
 		$aForbiddenValues = $aValues;
 		
-		$iDefaultKey = array_search($this->defaultValue, $this->aForbiddenValues);
+		$iDefaultKey = array_search($this->defaultValue, $aForbiddenValues);
 		if ($iDefaultKey !== false)
 		{
 			// The default (current) value is always allowed...