diff --git a/lib/carto/renderer_js.js b/lib/carto/renderer_js.js
index cf87965..3bdb885 100644
--- a/lib/carto/renderer_js.js
+++ b/lib/carto/renderer_js.js
@@ -56,6 +56,10 @@ CartoCSS.Layer.prototype = {
     return style;
   },
 
+  getShader: function() {
+    return this.shader;
+  },
+
   /**
    * returns true if a feature needs to be rendered
    */