diff --git a/src/osmo-bsc/osmo_bsc_bssap.c b/src/osmo-bsc/osmo_bsc_bssap.c
index 45861cc..0ecc11c 100644
--- a/src/osmo-bsc/osmo_bsc_bssap.c
+++ b/src/osmo-bsc/osmo_bsc_bssap.c
@@ -401,7 +401,7 @@
 	struct msgb *resp;
 	int reject_cause = -1;
 	int include_imeisv = 1;
-	uint8_t *enc_key;
+	const uint8_t *enc_key;
 	uint16_t enc_key_len;
 	uint8_t enc_bits_bsc;
 	uint8_t enc_bits_msc;