diff --git a/include/osmocom/gsm/protocol/gsm_12_21.h b/include/osmocom/gsm/protocol/gsm_12_21.h
index 5daab42b8..d6e8c11f7 100644
--- a/include/osmocom/gsm/protocol/gsm_12_21.h
+++ b/include/osmocom/gsm/protocol/gsm_12_21.h
@@ -275,6 +275,8 @@ enum abis_mm_event_causes {
 	OSMO_EVT_MIN_PAG_TAB_FULL	= 0x0401,
 	/* Warning causes */
 	OSMO_EVT_WARN_SW_WARN		= 0x0001,
+	/* External causes */
+	OSMO_EVT_EXT_ALARM		= 0xfeed,
 };
 
 extern const struct value_string abis_mm_event_cause_names[];
diff --git a/src/gsm/abis_nm.c b/src/gsm/abis_nm.c
index 9839d29b2..10aae9a78 100644
--- a/src/gsm/abis_nm.c
+++ b/src/gsm/abis_nm.c
@@ -161,6 +161,7 @@ const struct value_string abis_mm_event_cause_names[] = {
 	{ OSMO_EVT_MAJ_NET_CONGEST,	"Network congestion" },
 	{ OSMO_EVT_MIN_PAG_TAB_FULL,	"Paging table full" },
 	{ OSMO_EVT_WARN_SW_WARN,	"Software warning" },
+	{ OSMO_EVT_EXT_ALARM,		"External alarm" },
 	{ 0, NULL }
 };