diff --git a/common/framework/filters/HTMLFilter.php b/common/framework/filters/HTMLFilter.php
index 6da0eaa87..80d269cee 100644
--- a/common/framework/filters/HTMLFilter.php
+++ b/common/framework/filters/HTMLFilter.php
@@ -302,6 +302,7 @@ class HTMLFilter
 		$def->addAttribute('img', 'srcset', 'Text');
 		$def->addAttribute('img', 'data-file-srl', 'Number');
 		$def->addAttribute('iframe', 'allowfullscreen', 'Bool');
+		$def->addAttribute('iframe', 'allow', 'Text');
 
 		// Support contenteditable="false" (#1710)
 		$def->addAttribute('div', 'contenteditable', 'Enum#false');