diff --git a/lib/carto/renderer_js.js b/lib/carto/renderer_js.js
index ae840c4..ac4fea5 100644
--- a/lib/carto/renderer_js.js
+++ b/lib/carto/renderer_js.js
@@ -57,7 +57,7 @@ CartoCSS.Layer.prototype = {
   },
 
   /**
-   * return the symbolizers that need to be rendered with 
+   * return the symbolizers that need to be rendered with
    * this style. The order is the rendering order.
    * @returns a list with 3 possible values 'line', 'marker', 'polygon'
    */
@@ -99,7 +99,7 @@ CartoCSS.Layer.prototype = {
 
   //
   // given a geoemtry type returns the transformed one acording the CartoCSS
-  // For points there are two kind of types: point and sprite, the first one 
+  // For points there are two kind of types: point and sprite, the first one
   // is a circle, second one is an image sprite
   //
   // the other geometry types are the same than geojson (polygon, linestring...)
@@ -209,12 +209,6 @@ CartoCSS.prototype = {
                 var value = rule.value.value[0].value[0].value.value;
                 this.imageURLs.push(value);
             }
-
-            rule.toXML(parse_env, {});
-        } 
-
-        if (this.options.strict && parse_env.errors.message) {
-          throw new Error(parse_env.errors.message);
         }
 
         layer.frames = [];
@@ -244,6 +238,13 @@ CartoCSS.prototype = {
       var done = {};
       for(var i = 0; i < defs.length; ++i) {
         var def = defs[i];
+
+        def.toXML(parse_env, {});
+
+        if (this.options.strict && parse_env.errors.message) {
+          throw new Error(parse_env.errors.message);
+        }
+
         var k = defKey(def);
         var layer = layers[k];
         if(!done[k]) {