diff --git a/openbsc/include/openbsc/gsm_data.h b/openbsc/include/openbsc/gsm_data.h
index d7db887..05e0490 100644
--- a/openbsc/include/openbsc/gsm_data.h
+++ b/openbsc/include/openbsc/gsm_data.h
@@ -21,6 +21,7 @@
 	GSM_SECURITY_NOAVAIL,
 	GSM_SECURITY_AUTH_FAILED,
 	GSM_SECURITY_SUCCEEDED,
+	GSM_SECURITY_ALREADY,
 };
 
 struct msgb;
diff --git a/openbsc/src/libmsc/gsm_04_08.c b/openbsc/src/libmsc/gsm_04_08.c
index b69ab95..7f38be2 100644
--- a/openbsc/src/libmsc/gsm_04_08.c
+++ b/openbsc/src/libmsc/gsm_04_08.c
@@ -173,7 +173,7 @@
 		status = GSM_SECURITY_NOAVAIL;
 	} else if (conn->lchan->encr.alg_id > RSL_ENC_ALG_A5(0)) {
 		DEBUGP(DMM, "Requesting to secure an already secure channel");
-		status = GSM_SECURITY_SUCCEEDED;
+		status = GSM_SECURITY_ALREADY;
 	} else if (!ms_cm2_a5n_support(subscr->equipment.classmark2,
 	                               net->a5_encryption)) {
 		DEBUGP(DMM, "Subscriber equipment doesn't support requested encryption");
@@ -835,6 +835,7 @@
 			break;
 
 		case GSM_SECURITY_NOAVAIL:
+		case GSM_SECURITY_ALREADY:
 			rc = gsm48_tx_mm_serv_ack(conn);
 			break;