diff --git a/openbsc/src/gsm_04_08.c b/openbsc/src/gsm_04_08.c
index addfeb0..40505e6 100644
--- a/openbsc/src/gsm_04_08.c
+++ b/openbsc/src/gsm_04_08.c
@@ -1643,7 +1643,7 @@
 }
 
 int gsm48_send_rr_app_info(struct gsm_lchan *lchan, u_int8_t apdu_id,
-			   u_int8_t apdu_len, u_int8_t *apdu)
+			   u_int8_t apdu_len, const u_int8_t *apdu)
 {
 	struct msgb *msg = gsm48_msgb_alloc();
 	struct gsm48_hdr *gh;