diff --git a/openbsc/src/gprs/Makefile.am b/openbsc/src/gprs/Makefile.am
index a827b77..ab2517e 100644
--- a/openbsc/src/gprs/Makefile.am
+++ b/openbsc/src/gprs/Makefile.am
@@ -93,7 +93,6 @@
 	sgsn_ares.c \
 	slhc.c \
 	oap.c \
-	oap_messages.c \
 	gprs_llc_xid.c \
 	v42bis.c \
 	$(NULL)
diff --git a/openbsc/src/gprs/oap.c b/openbsc/src/gprs/oap.c
index c7c9777..7efbe81 100644
--- a/openbsc/src/gprs/oap.c
+++ b/openbsc/src/gprs/oap.c
@@ -24,10 +24,10 @@
 
 #include <osmocom/core/utils.h>
 #include <osmocom/crypt/auth.h>
+#include <osmocom/gsm/oap.h>
 
 #include <openbsc/oap.h>
 #include <openbsc/debug.h>
-#include <openbsc/oap_messages.h>
 
 int oap_init(struct oap_config *config, struct oap_state *state)
 {
diff --git a/openbsc/src/gprs/oap_messages.c b/openbsc/src/gprs/oap_messages.c
deleted file mode 100644
index d81723f..0000000
--- a/openbsc/src/gprs/oap_messages.c
+++ /dev/null
@@ -1,178 +0,0 @@
-/* Osmocom Authentication Protocol message encoder/decoder */
-
-/* (C) 2015 by Sysmocom s.f.m.c. GmbH
- * All Rights Reserved
- *
- * Author: Neels Hofmeyr
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as published by
- * the Free Software Foundation; either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-#include <osmocom/core/utils.h>
-#include <openbsc/oap_messages.h>
-
-#include <openbsc/debug.h>
-
-#include <osmocom/gsm/tlv.h>
-#include <osmocom/core/msgb.h>
-
-#include <stdint.h>
-
-
-int osmo_oap_decode(struct osmo_oap_message *oap_msg,
-		    const uint8_t *const_data, size_t data_len)
-{
-	int rc;
-	uint8_t tag;
-	/* the shift/match functions expect non-const pointers, but we'll
-	 * either copy the data or cast pointers back to const before returning
-	 * them
-	 */
-	uint8_t *data = (uint8_t *)const_data;
-	uint8_t *value;
-	size_t value_len;
-
-	memset(oap_msg, 0, sizeof(*oap_msg));
-
-	/* message type */
-	rc = osmo_shift_v_fixed(&data, &data_len, 1, &value);
-	if (rc < 0)
-		return -GMM_CAUSE_INV_MAND_INFO;
-	oap_msg->message_type = osmo_decode_big_endian(value, 1);
-
-	/* specific parts */
-	while (data_len > 0) {
-		enum oap_iei iei;
-
-		rc = osmo_shift_tlv(&data, &data_len, &tag, &value, &value_len);
-		if (rc < 0)
-			return -GMM_CAUSE_PROTO_ERR_UNSPEC;
-
-		iei = tag;
-
-		switch (iei) {
-		case OAP_CLIENT_ID_IE:
-			if (value_len != 2) {
-				LOGP(DGPRS, LOGL_NOTICE,
-				     "OAP IE type client ID (%d) should be 2 octets, but has %d\n",
-				     (int)iei, (int)value_len);
-				return -GMM_CAUSE_PROTO_ERR_UNSPEC;
-			}
-
-			oap_msg->client_id = osmo_decode_big_endian(value, value_len);
-
-			if (oap_msg->client_id == 0) {
-				LOGP(DGPRS, LOGL_NOTICE,
-				     "OAP IE type client ID (%d): client ID must be nonzero.\n",
-				     (int)iei);
-				return -GMM_CAUSE_PROTO_ERR_UNSPEC;
-			}
-			break;
-
-		case OAP_AUTN_IE:
-			if (value_len != sizeof(oap_msg->autn)) {
-				LOGP(DGPRS, LOGL_NOTICE,
-				     "OAP IE type AUTN (%d) should be %d octets, but has %d\n",
-				     (int)iei, (int)sizeof(oap_msg->autn), (int)value_len);
-				return -GMM_CAUSE_PROTO_ERR_UNSPEC;
-			}
-			memcpy(oap_msg->autn, value, value_len);
-			oap_msg->autn_present = value_len;
-			break;
-
-		case OAP_RAND_IE:
-			if (value_len != sizeof(oap_msg->rand)) {
-				LOGP(DGPRS, LOGL_NOTICE,
-				     "OAP IE type RAND (%d) should be %d octets, but has %d\n",
-				     (int)iei, (int)sizeof(oap_msg->rand), (int)value_len);
-				return -GMM_CAUSE_PROTO_ERR_UNSPEC;
-			}
-			memcpy(oap_msg->rand, value, value_len);
-			oap_msg->rand_present = value_len;
-			break;
-
-		case OAP_XRES_IE:
-			if (value_len != sizeof(oap_msg->xres)) {
-				LOGP(DGPRS, LOGL_NOTICE,
-				     "OAP IE type XRES (%d) should be %d octets, but has %d\n",
-				     (int)iei, (int)sizeof(oap_msg->xres), (int)value_len);
-				return -GMM_CAUSE_PROTO_ERR_UNSPEC;
-			}
-			memcpy(oap_msg->xres, value, value_len);
-			oap_msg->xres_present = value_len;
-			break;
-
-		case OAP_AUTS_IE:
-			if (value_len != sizeof(oap_msg->auts)) {
-				LOGP(DGPRS, LOGL_NOTICE,
-				     "OAP IE type AUTS (%d) should be %d octets, but has %d\n",
-				     (int)iei, (int)sizeof(oap_msg->auts), (int)value_len);
-				return -GMM_CAUSE_PROTO_ERR_UNSPEC;
-			}
-			memcpy(oap_msg->auts, value, value_len);
-			oap_msg->auts_present = value_len;
-			break;
-
-		case OAP_CAUSE_IE:
-			if (value_len > 1) {
-				LOGP(DGPRS, LOGL_ERROR,
-				     "OAP cause may not exceed one octet, is %d", (int)value_len);
-				return -GMM_CAUSE_PROTO_ERR_UNSPEC;
-			}
-			oap_msg->cause = *value;
-			break;
-
-		default:
-			LOGP(DGPRS, LOGL_NOTICE,
-			     "OAP IE type %d unknown\n", iei);
-			continue;
-		}
-	}
-
-	return 0;
-}
-
-void osmo_oap_encode(struct msgb *msg, const struct osmo_oap_message *oap_msg)
-{
-	uint8_t u8;
-
-	/* generic part */
-	OSMO_ASSERT(oap_msg->message_type);
-	msgb_v_put(msg, (uint8_t)oap_msg->message_type);
-
-	/* specific parts */
-	if ((u8 = oap_msg->cause))
-		msgb_tlv_put(msg, OAP_CAUSE_IE, sizeof(u8), &u8);
-
-	if (oap_msg->client_id > 0)
-		msgb_tlv_put(msg, OAP_CLIENT_ID_IE, sizeof(oap_msg->client_id),
-			     osmo_encode_big_endian(oap_msg->client_id,
-						    sizeof(oap_msg->client_id)));
-
-	if (oap_msg->rand_present)
-		msgb_tlv_put(msg, OAP_RAND_IE, sizeof(oap_msg->rand), oap_msg->rand);
-
-	if (oap_msg->autn_present)
-		msgb_tlv_put(msg, OAP_AUTN_IE, sizeof(oap_msg->autn), oap_msg->autn);
-
-	if (oap_msg->auts_present)
-		msgb_tlv_put(msg, OAP_AUTS_IE, sizeof(oap_msg->auts), oap_msg->auts);
-
-	if (oap_msg->xres_present)
-		msgb_tlv_put(msg, OAP_XRES_IE, sizeof(oap_msg->xres), oap_msg->xres);
-
-	msg->l2h = msg->data;
-}
-