diff --git a/superset/views/core.py b/superset/views/core.py
index be4cbefe8c49b..b49ef45648f22 100755
--- a/superset/views/core.py
+++ b/superset/views/core.py
@@ -78,7 +78,7 @@
     FORM_DATA_KEY_BLACKLIST = [
         'js_tooltip',
         'js_onclick_href',
-        'js_data_mutator'
+        'js_data_mutator',
     ]
 
 
@@ -956,7 +956,7 @@ def get_form_data(self):
 
         if request.args.get('viz_type'):
             # Converting old URLs
-            form_data_dict = cast_form_data(d)
+            d = cast_form_data(d)
 
         for k in FORM_DATA_KEY_BLACKLIST:
             if k in d: