diff --git a/parser/parser-cpmd/cpmdparser/tools/input_structure_generation.py b/parser/parser-cpmd/cpmdparser/tools/input_structure_generation.py
index dfcd95659945076d24b34fcf7b3fab49327fe373..9c7928445b2596ebdf6cd66efad96ce6f1b54f87 100644
--- a/parser/parser-cpmd/cpmdparser/tools/input_structure_generation.py
+++ b/parser/parser-cpmd/cpmdparser/tools/input_structure_generation.py
@@ -142,7 +142,7 @@ def generate_pickle(filepath):
     input_tree = generate_input_tree(filepath)
     file_name = "../versions/cpmd41/input_data/cpmd_input_tree.pickle"
     fh = open(file_name, "wb")
-    pickle.dump(input_tree, fh)
+    pickle.dump(input_tree, fh, protocol=2)
 
 
 #===============================================================================
diff --git a/parser/parser-cpmd/cpmdparser/versions/cpmd41/input_data/cpmd_input_tree.pickle b/parser/parser-cpmd/cpmdparser/versions/cpmd41/input_data/cpmd_input_tree.pickle
index 7159c1d24b103d98709690b2001b426629f63b19..8a8c72b451b3f17d6db135b266f42eb27aab7188 100644
Binary files a/parser/parser-cpmd/cpmdparser/versions/cpmd41/input_data/cpmd_input_tree.pickle and b/parser/parser-cpmd/cpmdparser/versions/cpmd41/input_data/cpmd_input_tree.pickle differ