diff --git a/openbsc/src/rs232.c b/openbsc/src/rs232.c
index bb940fe..7550571 100644
--- a/openbsc/src/rs232.c
+++ b/openbsc/src/rs232.c
@@ -54,7 +54,7 @@
 static int handle_ser_write(struct bsc_fd *bfd);
 
 /* callback from abis_nm */
-int _abis_nm_sendmsg(struct msgb *msg)
+int _abis_nm_sendmsg(struct msgb *msg, int to_trx_oml)
 {
 	struct serial_handle *sh = ser_handle;
 	u_int8_t *lapd;