diff --git a/lib/Parser/XML/Element/KeyValue.php b/lib/Parser/XML/Element/KeyValue.php
index c0bbf0d9b..e01772510 100644
--- a/lib/Parser/XML/Element/KeyValue.php
+++ b/lib/Parser/XML/Element/KeyValue.php
@@ -34,10 +34,8 @@ class KeyValue extends SabreXml\Element\KeyValue
      * the next element.
      *
      * @param XML\Reader $reader
-     *
-     * @return mixed
      */
-    public static function xmlDeserialize(SabreXml\Reader $reader)
+    public static function xmlDeserialize(SabreXml\Reader $reader): array
     {
         // If there's no children, we don't do anything.
         if ($reader->isEmptyElement) {