diff --git a/lib/class/xml_data.class.php b/lib/class/xml_data.class.php
index 7c31f807..b35e09ee 100644
--- a/lib/class/xml_data.class.php
+++ b/lib/class/xml_data.class.php
@@ -300,6 +300,9 @@ class XML_Data
      */
     public static function artists($artists, $include=[], $full_xml=true)
     {
+        if (null == $include) {
+            $include = array();
+        }
         $string = '<total_count>' . count($artists) . '</total_count>\n';
 
         if (count($artists) > self::$limit or self::$offset > 0) {
@@ -365,6 +368,9 @@ class XML_Data
      */
     public static function albums($albums, $include=[], $full_xml=true)
     {
+        if (null == $include) {
+            $include = array();
+        }
         $string = '<total_count>' . count($albums) . '</total_count>\n';
 
         if (count($albums) > self::$limit or self::$offset > 0) {