diff --git a/index.js b/index.js
index c8b562e..f2aa61f 100644
--- a/index.js
+++ b/index.js
@@ -1,7 +1,7 @@
 var camel2hyphen = require('string-convert/camel2hyphen');
 
 var isDimension = function (feature) {
-  var re = /[height|width]$/;
+  var re = /(height|width)$/i;
   return re.test(feature);
 };
 
@@ -48,4 +48,4 @@ var json2mq = function (query) {
   return obj2mq(query);
 };
 
-module.exports = json2mq;
\ No newline at end of file
+module.exports = json2mq;