diff --git a/include/osmocom/gsm/protocol/gsm_04_08_gprs.h b/include/osmocom/gsm/protocol/gsm_04_08_gprs.h
index a3434c6..65dc233 100644
--- a/include/osmocom/gsm/protocol/gsm_04_08_gprs.h
+++ b/include/osmocom/gsm/protocol/gsm_04_08_gprs.h
@@ -83,6 +83,7 @@
 enum gsm48_gprs_ie_mm {
 	GSM48_IE_GMM_CIPH_CKSN		= 0x08, /* 10.5.1.2 */
 	GSM48_IE_GMM_PTMSI_TYPE		= 0x0e, /* 10.5.5.29 */
+	GSM48_IE_GMM_TMSI_BASED_NRI_C	= 0x10, /* 10.5.5.31 */
 	GSM48_IE_GMM_TIMER_READY	= 0x17,	/* 10.5.7.3 */
 	GSM48_IE_GMM_ALLOC_PTMSI	= 0x18,	/* 10.5.1.4 */
 	GSM48_IE_GMM_PTMSI_SIG		= 0x19,	/* 10.5.5.8 */