diff --git a/pypechain/main.py b/pypechain/main.py
index 82191d2b..9ffa07b4 100644
--- a/pypechain/main.py
+++ b/pypechain/main.py
@@ -118,8 +118,12 @@ def parse_arguments(argv: Sequence[str] | None = None) -> Args:
         ),
     )
 
+    # Use system arguments if none were passed
+    if argv is None:
+        argv = sys.argv
+
     # If no arguments were passed, display the help message and exit
-    if len(sys.argv) == 1:
+    if len(argv) == 1:
         parser.print_help(sys.stderr)
         sys.exit(1)