diff --git a/src/htmlminifier.js b/src/htmlminifier.js
index c7928426..ab69aa59 100644
--- a/src/htmlminifier.js
+++ b/src/htmlminifier.js
@@ -199,7 +199,7 @@ function isStyleSheet(tag, attrs) {
   return true;
 }
 
-var isSimpleBoolean = createMapFromString('allowfullscreen,async,autofocus,autoplay,checked,compact,controls,declare,default,defaultchecked,defaultmuted,defaultselected,defer,disabled,enabled,formnovalidate,hidden,indeterminate,inert,ismap,itemscope,loop,multiple,muted,nohref,noresize,noshade,novalidate,nowrap,open,pauseonexit,readonly,required,reversed,scoped,seamless,selected,sortable,truespeed,typemustmatch,visible');
+var isSimpleBoolean = createMapFromString('allowfullscreen,async,autofocus,autoplay,checked,compact,controls,declare,default,defaultchecked,defaultmuted,defaultselected,defer,disabled,enabled,formnovalidate,hidden,indeterminate,inert,ismap,itemscope,loop,multiple,muted,nohref,noresize,noshade,novalidate,nowrap,open,pauseonexit,readonly,required,reversed,scoped,seamless,selected,sortable,truespeed,typemustmatch,visible,⚡,amp,amp-boilerplate,amp-custom');
 var isBooleanValue = createMapFromString('true,false');
 
 function isBooleanAttribute(attrName, attrValue) {