diff --git a/superset/models/helpers.py b/superset/models/helpers.py
index aeb1e4f0705..72ce09a390d 100644
--- a/superset/models/helpers.py
+++ b/superset/models/helpers.py
@@ -1979,7 +1979,7 @@ class ExploreMixin:  # pylint: disable=too-many-public-methods
             if offset_metrics_df.empty:
                 offset_metrics_df = pd.DataFrame(
                     {
-                        col: [np.NaN]
+                        col: [np.nan]
                         for col in join_keys + list(metrics_mapping.values())
                     }
                 )