diff --git a/chirp/drivers/ft1d.py b/chirp/drivers/ft1d.py
index d034d9773..f50ed1f31 100644
--- a/chirp/drivers/ft1d.py
+++ b/chirp/drivers/ft1d.py
@@ -2358,7 +2358,7 @@ def _apply_callsign(cls, callsign, obj, default_ssid=None):
                 ssid = int(ssid) % 16
             except ValueError:
                 ssid = default_ssid
-        setattr(obj, "callsign", cls._add_ff_pad(callsign, 6))
+        setattr(obj, "callsign", cls._add_ff_pad(callsign.encode(), 6))
         if ssid is not None:
             setattr(obj, "ssid", ssid)