diff --git a/openbsc/src/abis_nm.c b/openbsc/src/abis_nm.c
index 6f112e1..f7fac63 100644
--- a/openbsc/src/abis_nm.c
+++ b/openbsc/src/abis_nm.c
@@ -2121,7 +2121,7 @@
 int abis_nm_perform_test(struct gsm_bts *bts, u_int8_t obj_class,
 			 u_int8_t bts_nr, u_int8_t trx_nr, u_int8_t ts_nr,
 			 u_int8_t test_nr, u_int8_t auton_report,
-			 u_int8_t *phys_config, u_int16_t phys_config_len)
+			 const u_int8_t *phys_config, u_int16_t phys_config_len)
 {
 	struct abis_om_hdr *oh;
 	struct msgb *msg = nm_msgb_alloc();