diff --git a/selfdrive/debug/check_can_parser_performance.py b/selfdrive/debug/check_can_parser_performance.py
index c4b688ce29..604a1df124 100755
--- a/selfdrive/debug/check_can_parser_performance.py
+++ b/selfdrive/debug/check_can_parser_performance.py
@@ -25,11 +25,12 @@ if __name__ == '__main__':
   CC = car.CarControl.new_message()
   ets = []
   for _ in tqdm(range(N_RUNS)):
+    msgs = [(m.as_builder().to_bytes(),) for m in tm.can_msgs]
     start_t = time.process_time_ns()
-    for msg in tm.can_msgs:
+    for msg in msgs:
       for cp in tm.CI.can_parsers:
         if cp is not None:
-          cp.update_strings((msg.as_builder().to_bytes(),))
+          cp.update_strings(msg)
     ets.append((time.process_time_ns() - start_t) * 1e-6)
 
   print(f'{len(tm.can_msgs)} CAN packets, {N_RUNS} runs')