diff --git a/bind/G4Calo.py b/bind/G4Calo.py
index 9925618..4534b1d 100644
--- a/bind/G4Calo.py
+++ b/bind/G4Calo.py
@@ -214,7 +214,7 @@ def run_batch(
     assert (n_ex_non_zero==n_unique), f"only {n_unique} unique non-zero entries in total_dep_energy out of {n_ex_non_zero}"
 
     if len(filename):
-        df.to_pickle(filename)
+        alldf.to_pickle(filename)
     
     return alldf