diff --git a/source/Editor.js b/source/Editor.js
index 3f2ba54..f52609e 100644
--- a/source/Editor.js
+++ b/source/Editor.js
@@ -986,7 +986,7 @@
         }
     };
 
-    var allowedBlock = /^A(?:DDRESS|RTICLE|SIDE)|BLOCKQUOTE|CAPTION|D(?:[DLT]|IV)|F(?:IGURE|OOTER)|H[1-6]|HEADER|L(?:ABEL|EGEND|I)|O(?:L|UTPUT)|P(?:RE)?|SECTION|T(?:ABLE|BODY|D|FOOT|H|HEAD|R)|UL$/;
+    var allowedBlock = /^(?:A(?:DDRESS|RTICLE|SIDE)|BLOCKQUOTE|CAPTION|D(?:[DLT]|IV)|F(?:IGURE|OOTER)|H[1-6]|HEADER|L(?:ABEL|EGEND|I)|O(?:L|UTPUT)|P(?:RE)?|SECTION|T(?:ABLE|BODY|D|FOOT|H|HEAD|R)|UL)$/;
 
     var fontSizes = {
         1: 10,