diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c
index 9551335..6e6b03b 100644
--- a/openbsc/src/gprs/gb_proxy.c
+++ b/openbsc/src/gprs/gb_proxy.c
@@ -462,8 +462,8 @@
 	if (link_info->imsi_acq_pending && link_info->imsi_len > 0) {
 		int is_ident_resp =
 			parse_ctx->g48_hdr &&
-			parse_ctx->g48_hdr->proto_discr == GSM48_PDISC_MM_GPRS &&
-			parse_ctx->g48_hdr->msg_type == GSM48_MT_GMM_ID_RESP;
+			gsm48_hdr_pdisc(parse_ctx->g48_hdr) == GSM48_PDISC_MM_GPRS &&
+			gsm48_hdr_msg_type(parse_ctx->g48_hdr) == GSM48_MT_GMM_ID_RESP;
 
 		/* The IMSI is now available */
 		gbproxy_flush_stored_messages(peer, msg, now, link_info,
diff --git a/openbsc/src/gprs/gprs_gb_parse.c b/openbsc/src/gprs/gprs_gb_parse.c
index 6096854..63ac902 100644
--- a/openbsc/src/gprs/gprs_gb_parse.c
+++ b/openbsc/src/gprs/gprs_gb_parse.c
@@ -329,17 +329,20 @@
 		       struct gprs_gb_parse_context *parse_ctx)
 {
 	struct gsm48_hdr *g48h;
+	uint8_t pdisc;
+	uint8_t msg_type;
 
 	if (gprs_shift_v_fixed(&data, &data_len, sizeof(*g48h), (uint8_t **)&g48h) <= 0)
 		return 0;
 
 	parse_ctx->g48_hdr = g48h;
 
-	if ((g48h->proto_discr & 0x0f) != GSM48_PDISC_MM_GPRS &&
-	    (g48h->proto_discr & 0x0f) != GSM48_PDISC_SM_GPRS)
+	pdisc = gsm48_hdr_pdisc(g48h);
+	if (pdisc != GSM48_PDISC_MM_GPRS && pdisc != GSM48_PDISC_SM_GPRS)
 		return 1;
 
-	switch (g48h->msg_type) {
+	msg_type = gsm48_hdr_msg_type(g48h);
+	switch (msg_type) {
 	case GSM48_MT_GMM_ATTACH_REQ:
 		return gprs_gb_parse_gmm_attach_req(data, data_len, parse_ctx);
 
@@ -376,6 +379,10 @@
 		break;
 
 	default:
+		LOGP(DLLC, LOGL_NOTICE,
+		     "Unknown GSM 04.08 message type 0x%02hhx for protocol"
+		     " discriminator 0x%02hhx.\n",
+		     msg_type, pdisc);
 		break;
 	};
 
diff --git a/openbsc/src/gprs/gprs_gmm.c b/openbsc/src/gprs/gprs_gmm.c
index d93ba3f..9d94c24 100644
--- a/openbsc/src/gprs/gprs_gmm.c
+++ b/openbsc/src/gprs/gprs_gmm.c
@@ -2089,7 +2089,7 @@
 int gsm0408_gprs_rcvmsg(struct msgb *msg, struct gprs_llc_llme *llme)
 {
 	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_gmmh(msg);
-	uint8_t pdisc = gh->proto_discr & 0x0f;
+	uint8_t pdisc = gsm48_hdr_pdisc(gh);
 	struct sgsn_mm_ctx *mmctx;
 	struct gprs_ra_id ra_id;
 	int rc = -EINVAL;