diff --git a/sys/fs/unionfs/union_vnops.c b/sys/fs/unionfs/union_vnops.c
index c8240e9973a..89673dff2cb 100644
--- a/sys/fs/unionfs/union_vnops.c
+++ b/sys/fs/unionfs/union_vnops.c
@@ -972,6 +972,8 @@ union_getattr(ap)
 		union_newsize(ap->a_vp, VNOVAL, vap->va_size);
 	}
 
+	ap->a_vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0];
+
 	if ((vap != ap->a_vap) && (vap->va_type == VDIR))
 		ap->a_vap->va_nlink += vap->va_nlink;
 	return (0);