diff --git a/sys/fs/nfs/nfsproto.h b/sys/fs/nfs/nfsproto.h
index ca9c732b6a4..0268940fd8a 100644
--- a/sys/fs/nfs/nfsproto.h
+++ b/sys/fs/nfs/nfsproto.h
@@ -1004,7 +1004,7 @@ struct nfsv3_sattr {
 #define	NFSATTRBIT_SPACEFREED		78
 #define	NFSATTRBIT_CHANGEATTRTYPE	79
 #define	NFSATTRBIT_SECLABEL		80
-/* Not sure what attribute bit #81 is? */
+#define	NFSATTRBIT_MODEUMASK		81
 #define	NFSATTRBIT_XATTRSUPPORT		82
 
 #define	NFSATTRBM_SUPPORTEDATTRS	0x00000001
@@ -1088,7 +1088,7 @@ struct nfsv3_sattr {
 #define	NFSATTRBM_SPACEFREED		0x00004000
 #define	NFSATTRBM_CHANGEATTRTYPE	0x00008000
 #define	NFSATTRBM_SECLABEL		0x00010000
-/* Not sure what attribute bit#81/0x00020000 is? */
+#define	NFSATTRBM_MODEUMASK		0x00020000
 #define	NFSATTRBM_XATTRSUPPORT		0x00040000
 
 #define	NFSATTRBIT_MAX			83