diff --git a/stat/correlation.py b/stat/correlation.py
index 91a0f33..d492534 100644
--- a/stat/correlation.py
+++ b/stat/correlation.py
@@ -33,7 +33,7 @@ def calculate_correlation(df: pd.DataFrame, target_id: str | None = None) -> pd.
     def max_abs_corr(group: pd.DataFrame) -> pd.Series:
         corr_arr = np.abs(group.corr().to_numpy().copy())
         np.fill_diagonal(corr_arr, 0.0)
-        return pd.Series(corr_arr.max(axis=0), index=group.columns)
+        return pd.Series(corr_arr.max(axis=0), index=group.columns).fillna(0.0)
 
     return df_bytes.groupby("Identifier")[available_cols].apply(max_abs_corr)