diff --git a/lib/HTMLUtils.php b/lib/HTMLUtils.php
index 9f097230..2b25acb6 100644
--- a/lib/HTMLUtils.php
+++ b/lib/HTMLUtils.php
@@ -133,8 +133,14 @@ class HTMLSanitizer {
 	var $keptAttributes;
 	var $onlyKeepText;
 
+/*
+// disabled due to PHP <5.6 breakage
 	const DEFAULT_CLEAR_TAGS = ["script", "iframe"];
 	const KEPT_ATTRIBUTES = ["title", "href", "src"];
+*/
+	const DEFAULT_CLEAR_TAGS = null;
+	const KEPT_ATTRIBUTES = null;
+// -----------------------------------------------
 
 	const ONLY_TEXT = null;