--- typo3/sysext/cms/tslib/class.tslib_content.php	2011-02-23 14:20:09.000000000 +0000
+++ typo3/sysext/cms/tslib/class.tslib_content.php	2011-05-20 00:25:59.000000000 +0100
@@ -4329,7 +4329,7 @@
 				</?(?:". $tags . ")+			# opening tag ('<tag') or closing tag ('</tag')
 				(?:
 					(?:
-						\s+\w+					# EITHER spaces, followed by word characters (attribute names)
+						\s+(?:\w+|-)					# EITHER spaces, followed by word characters (attribute names)
 						(?:
 							\s*=?\s*			# equals
 							(?>