diff --git a/bridges/s3-bridge/s3_bridge.py b/bridges/s3-bridge/s3_bridge.py
index 733eb21..0f813c4 100644
--- a/bridges/s3-bridge/s3_bridge.py
+++ b/bridges/s3-bridge/s3_bridge.py
@@ -307,8 +307,8 @@ def annotation_loop(logger: SessionLogger, stop: threading.Event) -> None:
 
 def main() -> int:
     ap = argparse.ArgumentParser()
-    ap.add_argument("--bw", default="COM5", help="Blastware-side COM port (default: COM5)")
-    ap.add_argument("--s3", default="COM4", help="S3-side COM port (default: COM4)")
+    ap.add_argument("--bw", default="COM4", help="Blastware-side COM port (default: COM4)")
+    ap.add_argument("--s3", default="COM5", help="S3-side COM port (default: COM5)")
     ap.add_argument("--baud", type=int, default=38400, help="Baud rate (default: 38400)")
     ap.add_argument("--logdir", default=".", help="Directory to write session logs into (default: .)")
     ap.add_argument("--quiet", action="store_true", help="No console heartbeat output")