diff --git a/src/manta/__init__.py b/src/manta/__init__.py
index 3d9a571..72eb77e 100644
--- a/src/manta/__init__.py
+++ b/src/manta/__init__.py
@@ -329,8 +329,8 @@ Supported commands:
 
             # sometimes macOS will enumerate non-serial devices as serial ports,
             # in which case the PID/VID/serial/location/etc are all None
-            pid = "0x{port.vid:04X}" if port.pid is not None else "None"
-            vid = "0x{port.vid:04X}" if port.vid is not None else "None"
+            pid = f"0x{port.vid:04X}" if port.pid is not None else "None"
+            vid = f"0x{port.vid:04X}" if port.vid is not None else "None"
 
             print(f" ->  pid: {pid}")
             print(f" ->  vid: {vid}")