diff --git a/src/msg_client.py b/src/msg_client.py
index 8c20e89..888a1a1 100644
--- a/src/msg_client.py
+++ b/src/msg_client.py
@@ -15,7 +15,7 @@ to_join = []
 parser = argparse.ArgumentParser(description="Msg client")
 parser.add_argument("-s", "--sleep", type=float, help="sleep time between two sendings", default=5.0)
 parser.add_argument("-n", "--nb", type=int, help="number of requests done", default=5)
-parser.add_argument("-B", "--bulk", type=bool, help="if set, don't wait for reply to send another packet", default=False)
+parser.add_argument("-B", "--bulk", help="if set, don't wait for reply to send another packet", action="store_true")
 
 args = parser.parse_args()