diff --git a/recopytex/datalib/on_score_column.py b/recopytex/datalib/on_score_column.py
index 6cedb84..6a05c89 100644
--- a/recopytex/datalib/on_score_column.py
+++ b/recopytex/datalib/on_score_column.py
@@ -2,7 +2,7 @@
 # encoding: utf-8
 
 from math import ceil
-import numpy as np
+import pandas as pd
 
 
 def is_none_score(x, score_config):
@@ -40,7 +40,7 @@ def is_none_score(x, score_config):
         for v in score_config.values()
         if str(v["numeric_value"]).lower() == "none"
     ]
-    return x["score"] in none_values or x["score"] is None or np.isnan(x["score"])
+    return x["score"] in none_values or pd.isnull(x["score"])
 
 
 def score_to_numeric_score(x, score_config):