diff --git a/OpenGraph.php b/OpenGraph.php
index af2e7b6..24b04a3 100644
--- a/OpenGraph.php
+++ b/OpenGraph.php
@@ -157,7 +157,7 @@ public function __get($key) {
 		}
 		
 		if ($key === 'schema') {
-			foreach (self::$TYPES AS $schema => $types) {
+			foreach (!empty($this->_values['type']) && self::$TYPES AS $schema => $types) {
 				if (array_search($this->_values['type'], $types)) {
 					return $schema;
 				}