diff --git a/php/classes/class-qsm-quiz-api.php b/php/classes/class-qsm-quiz-api.php
index a3d32aaa8..63013af1f 100644
--- a/php/classes/class-qsm-quiz-api.php
+++ b/php/classes/class-qsm-quiz-api.php
@@ -388,12 +388,14 @@ public function qsm_unserialize_to_api_format( $data ) {
 		if ( is_serialized($data) ) {
 			return maybe_unserialize($data);
 		}
-	
-		foreach ( $data as $key => $value ) {
-			if ( is_serialized($value) ) {
-				$result[ $key ] = $this->qsm_unserialize_recursive_loop($value);
-			} else {
-				$result[ $key ] = $value;
+
+		if ( is_array($data) || is_object($data) ) {
+			foreach ( $data as $key => $value ) {
+				if ( is_serialized($value) ) {
+					$result[ $key ] = $this->qsm_unserialize_recursive_loop($value);
+				} else {
+					$result[ $key ] = $value;
+				}
 			}
 		}