diff --git a/include/osmocom/bsc/abis_rsl.h b/include/osmocom/bsc/abis_rsl.h
index ba44669..5ada3fc 100644
--- a/include/osmocom/bsc/abis_rsl.h
+++ b/include/osmocom/bsc/abis_rsl.h
@@ -61,8 +61,8 @@
 int rsl_siemens_mrpci(struct gsm_lchan *lchan, struct rsl_mrpci *mrpci);
 
 /* ip.access specfic RSL extensions */
-int rsl_tx_ipacc_crcx(struct gsm_lchan *lchan);
-int rsl_tx_ipacc_mdcx(struct gsm_lchan *lchan);
+int rsl_tx_ipacc_crcx(const struct gsm_lchan *lchan);
+int rsl_tx_ipacc_mdcx(const struct gsm_lchan *lchan);
 int rsl_ipacc_mdcx_to_rtpsock(struct gsm_lchan *lchan);
 int rsl_ipacc_pdch_activate(struct gsm_bts_trx_ts *ts, int act);
 
diff --git a/src/osmo-bsc/abis_rsl.c b/src/osmo-bsc/abis_rsl.c
index 2eda884..bd104ed 100644
--- a/src/osmo-bsc/abis_rsl.c
+++ b/src/osmo-bsc/abis_rsl.c
@@ -1830,7 +1830,7 @@
 /*! Send Issue IPA RSL CRCX to configure the RTP port of the BTS.
  * \param[in] lchan Logical Channel for which we issue CRCX
  */
-int rsl_tx_ipacc_crcx(struct gsm_lchan *lchan)
+int rsl_tx_ipacc_crcx(const struct gsm_lchan *lchan)
 {
 	struct msgb *msg = rsl_msgb_alloc();
 	struct abis_rsl_dchan_hdr *dh;
@@ -1856,7 +1856,7 @@
  * \param[in] lchan Logical Channel for which we issue MDCX
  * Remote (MGW) IP address, port and payload types for RTP are determined from lchan->abis_ip.
  */
-int rsl_tx_ipacc_mdcx(struct gsm_lchan *lchan)
+int rsl_tx_ipacc_mdcx(const struct gsm_lchan *lchan)
 {
 	struct msgb *msg = rsl_msgb_alloc();
 	struct abis_rsl_dchan_hdr *dh;
diff --git a/tests/gsm0408/gsm0408_test.c b/tests/gsm0408/gsm0408_test.c
index faeca39..f2b85e4 100644
--- a/tests/gsm0408/gsm0408_test.c
+++ b/tests/gsm0408/gsm0408_test.c
@@ -968,7 +968,7 @@
 
 int rsl_chan_mode_modify_req(struct gsm_lchan *ts) { return 0; }
 
-int rsl_tx_ipacc_crcx(struct gsm_lchan *lchan) { return 0; }
+int rsl_tx_ipacc_crcx(const struct gsm_lchan *lchan) { return 0; }
 
 void gscon_submit_rsl_dtap(struct gsm_subscriber_connection *conn,
 			   struct msgb *msg, int link_id, int allow_sacch) {}