diff --git a/include/openbsc/abis_nm.h b/include/openbsc/abis_nm.h
index 5d09172..c280c89 100644
--- a/include/openbsc/abis_nm.h
+++ b/include/openbsc/abis_nm.h
@@ -191,6 +191,7 @@
 
 	NM_MT_BS11_SET_ATTR		= 0xd0,
 	NM_MT_BS11_SET_ATTR_ACK,
+	NM_MT_BS11_SET_ATTR_NACK,
 	NM_MT_BS11_LMT_SESSION		= 0xdc,
 
 	NM_MT_BS11_GET_STATE		= 0xe3,