diff --git a/src/rig.c b/src/rig.c
index c7c4ae36f..6eb923386 100644
--- a/src/rig.c
+++ b/src/rig.c
@@ -377,6 +377,7 @@ RIG * HAMLIB_API rig_init(rig_model_t rig_model)
     case RIG_PORT_CM108:
         strncpy(rs->rigport.pathname, DEFAULT_CM108_PORT, FILPATHLEN);
         rs->rigport.parm.cm108.ptt_bitnum = DEFAULT_CM108_PTT_BITNUM;
+        rs->pttport.parm.cm108.ptt_bitnum = DEFAULT_CM108_PTT_BITNUM;
         break;
 
     case RIG_PORT_GPIO: