diff --git a/include/openbsc/gsm_data.h b/include/openbsc/gsm_data.h
index 7500958..a838c79 100644
--- a/include/openbsc/gsm_data.h
+++ b/include/openbsc/gsm_data.h
@@ -150,8 +150,7 @@
 
 	void (*update_request_accepted)(struct gsm_bts *, u_int32_t);
 	void (*channel_allocated)(struct gsm_lchan *bts, enum gsm_chreq_reason_t);
-	void (*channel_acked)(struct gsm_lchan *);
-	void (*channel_nacked)(struct gsm_lchan *);
+	void (*channel_response)(struct gsm_lchan *, int acked);
 };
 
 struct gsm_network *gsm_network_init(unsigned int num_bts, u_int16_t country_code,