diff --git a/include/osmocom/sgsn/gprs_gmm.h b/include/osmocom/sgsn/gprs_gmm.h
index d12eaf9..ffcebd3 100644
--- a/include/osmocom/sgsn/gprs_gmm.h
+++ b/include/osmocom/sgsn/gprs_gmm.h
@@ -40,6 +40,8 @@
 				uint8_t gmm_cause);
 int gsm48_tx_gmm_att_ack(struct sgsn_mm_ctx *mm);
 
+int gprs_gmm_attach_req_ies(struct msgb *a, struct msgb *b);
+
 /* TODO: move extract_subscr_* when gsm48_gmm_authorize() got removed */
 void extract_subscr_msisdn(struct sgsn_mm_ctx *ctx);
 void extract_subscr_hlr(struct sgsn_mm_ctx *ctx);