diff --git a/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js b/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js
index 0390536b..ad415c55 100644
--- a/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js
+++ b/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js
@@ -260,19 +260,18 @@ function fieldType(cname) {
 
 // columns are returned as an object { columnName1: { type1: ...}, ..}
 // for consistency with SQL API
-function formatResultFields(dbConnection, flds) {
-    flds = flds || [];
-    var nfields = {};
-    for (var i=0; i<flds.length; ++i) {
-      var f = flds[i];
-      var cname = dbConnection.typeName(f.dataTypeID);
-      var tname;
+function formatResultFields(dbConnection, fields = []) {
+    let nfields = {};
+    for (let field of fields) {
+      const cname = dbConnection.typeName(field.dataTypeID);
+      console.log("FIELD",field);
+      let tname;
       if ( ! cname ) {
-        tname = 'unknown(' + f.dataTypeID + ')';
+        tname = 'unknown(' + field.dataTypeID + ')';
       } else {
         tname = fieldType(cname);
       }
-      nfields[f.name] = { type: tname };
+      nfields[field.name] = { type: tname };
     }
     return nfields;
 }