diff --git a/lib/pypechain/pypechain/run_pypechain.py b/lib/pypechain/pypechain/run_pypechain.py
index a21d85989..73c17e7c0 100644
--- a/lib/pypechain/pypechain/run_pypechain.py
+++ b/lib/pypechain/pypechain/run_pypechain.py
@@ -48,8 +48,8 @@ def main(abi_file_path: str, output_dir: str) -> None:
     # TODO:  events
 
     # Write the renders to a file
-    types_output_file_path = Path(output_dir).joinpath(contract_name + "Types.py")
-    contract_output_file_path = Path(output_dir).joinpath(contract_name + "Contract.py")
+    types_output_file_path = Path(output_dir).joinpath(f"{contract_name}Types.py")
+    contract_output_file_path = Path(output_dir).joinpath(f"{contract_name}Contract.py")
     with open(contract_output_file_path, "w", encoding="utf-8") as output_file:
         output_file.write(rendered_contract_code)
     with open(types_output_file_path, "w", encoding="utf-8") as output_file: