diff --git a/include/openbsc/rs232.h b/include/openbsc/rs232.h
index deb0c6b..61187ca 100644
--- a/include/openbsc/rs232.h
+++ b/include/openbsc/rs232.h
@@ -1,7 +1,8 @@
 #ifndef _RS232_H
 #define _RS232_H
 
-int rs232_setup(const char *serial_port, unsigned int delay_ms);
+int rs232_setup(const char *serial_port, unsigned int delay_ms,
+		struct gsm_bts *bts);
 
 int handle_serial_msg(struct msgb *msg);