diff --git a/tnc/modem.py b/tnc/modem.py
index 0930b8e4..b2c42c5c 100644
--- a/tnc/modem.py
+++ b/tnc/modem.py
@@ -380,7 +380,7 @@ class RF():
         state_before_transmit = static.CHANNEL_STATE
         static.CHANNEL_STATE = 'SENDING_DATA'
 
-        freedv = cast(self.c_lib.freedv_open(freedv_signalling_mode), c_void_p)
+        freedv = cast(self.c_lib.freedv_open(mode), c_void_p)
         self.c_lib.freedv_set_clip(freedv, 1)
         self.c_lib.freedv_set_tx_bpf(freedv, 1)