diff --git a/fs/nfsd/nfs4acl.c b/fs/nfsd/nfs4acl.c
index d714156a19fd..b0cf00d3ee7d 100644
--- a/fs/nfsd/nfs4acl.c
+++ b/fs/nfsd/nfs4acl.c
@@ -935,5 +935,5 @@ __be32 nfs4_acl_write_who(struct xdr_stream *xdr, int who)
 		return 0;
 	}
 	WARN_ON_ONCE(1);
-	return -1;
+	return nfserr_serverfault;
 }