diff --git a/src/directives/mapbox.directive.js b/src/directives/mapbox.directive.js
index 883cd92..172273e 100644
--- a/src/directives/mapbox.directive.js
+++ b/src/directives/mapbox.directive.js
@@ -21,8 +21,8 @@
 
         var mapWidth = attrs.width || 500;
         var mapHeight = attrs.height || 500;
-        element.css('width', mapWidth + 'px');
-        element.css('height', mapHeight + 'px');
+        element.css('width', mapWidth + (/^[0-9]+$/.test(mapWidth)?'px':''));
+        element.css('height', mapHeight + (/^[0-9]+$/.test(mapHeight)?'px':''));
 
         scope.zoom = attrs.zoom || 12;
         if(attrs.lat && attrs.lng) {