--- runtime/syntax/yacc.vim	2014-03-09 13:39:47.000000000 -0700
+++ runtime/syntax/yacc.vim	2014-03-09 13:42:16.000000000 -0700
@@ -42,7 +42,7 @@
 " ---------------------------------------------------------------------
 "  Yacc Clusters: {{{1
 syn cluster yaccInitCluster	contains=yaccKey,yaccKeyActn,yaccBrkt,yaccType,yaccString,yaccUnionStart,yaccHeader2,yaccComment,yaccDefines,yaccParseParam,yaccParseOption
-syn cluster yaccRulesCluster	contains=yaccNonterminal,yaccString
+syn cluster yaccRulesCluster	contains=yaccNonterminal,yaccString,yaccComment
 
 " ---------------------------------------------------------------------
 "  Yacc Sections: {{{1