diff --git a/superset/viz.py b/superset/viz.py
index 0b29fd2de7f8..a82ddc15abde 100755
--- a/superset/viz.py
+++ b/superset/viz.py
@@ -1142,7 +1142,7 @@ def get_data(self, df):
             d = {
                 "key": series_title,
                 "values": [
-                    {'x': str(row.index[i]), 'y': v}
+                    {'x': str(i), 'y': v}
                     for i, v in ys.iteritems()]
             }
             chart_data.append(d)