diff --git a/src/converter/pytorch_converter.py b/src/converter/pytorch_converter.py
index 2652ca3e..7d49c7c4 100644
--- a/src/converter/pytorch_converter.py
+++ b/src/converter/pytorch_converter.py
@@ -81,7 +81,7 @@ def initialize_attributes(self) -> None:
         self.pytorch_time = None
         self.pytorch_start_ts = None
         self.pytorch_finish_ts = None
-        self.pytorch_nodes = None
+        self.pytorch_nodes = dict()
         self.pytorch_root_nids = []
 
         # Initialize node mapping dictionaries