diff --git a/src/gsm/gsm0808.c b/src/gsm/gsm0808.c
index 3c77c77..514d7f2 100644
--- a/src/gsm/gsm0808.c
+++ b/src/gsm/gsm0808.c
@@ -1387,6 +1387,10 @@
 		[GSM0808_IE_CN_TO_MS_TRANSP_INFO]	= { TLV_TYPE_TLV },
 		[GSM0808_IE_SELECTED_PLMN_ID]		= { TLV_TYPE_FIXED, 3 },
 		[GSM0808_IE_LAST_USED_EUTRAN_PLMN_ID]	= { TLV_TYPE_FIXED, 3 },
+
+		/* Osmocom extensions */
+		[GSM0808_IE_OSMO_OSMUX_SUPPORT]		= { TLV_TYPE_T },
+		[GSM0808_IE_OSMO_OSMUX_CID]		= { TLV_TYPE_TV },
 	},
 };