diff --git a/src/Util/XML.php b/src/Util/XML.php
index 095d5cad71..7d18277633 100644
--- a/src/Util/XML.php
+++ b/src/Util/XML.php
@@ -168,7 +168,7 @@ class XML
 
 		foreach ($attributes as $key => $value) {
 			$attribute = $doc->createAttribute($key);
-			$attribute->value = self::escape($value);
+			$attribute->value = self::escape($value ?? '');
 			$element->appendChild($attribute);
 		}
 		return $element;