diff --git a/modules/adfs/www/idp/prp.php b/modules/adfs/www/idp/prp.php
index c758113081e3f0743ba71d26a822782676332a4f..4cec12fedd8ae61a2fb36755645dd32060c53ca9 100644
--- a/modules/adfs/www/idp/prp.php
+++ b/modules/adfs/www/idp/prp.php
@@ -55,7 +55,7 @@ function ADFS_GenerateResponse($issuer, $target, $nameid, $attributes) {
 		$hasValue = FALSE;
 		$r = '<saml:Attribute AttributeNamespace="http://schemas.xmlsoap.org/claims" AttributeName="' . htmlspecialchars($name) .'">';
 		foreach ($values as $value) {
-			if (isset($value) or ($value !== '')) continue;
+			if ( (!isset($value)) or ($value === '')) continue;
 			$r .= '<saml:AttributeValue>' . htmlspecialchars($value) . '</saml:AttributeValue>';
 			$hasValue = TRUE;
 		}