diff --git a/net/mptcp/token_test.c b/net/mptcp/token_test.c
index 5d984bec1cd8..0758865ab658 100644
--- a/net/mptcp/token_test.c
+++ b/net/mptcp/token_test.c
@@ -57,6 +57,9 @@ static struct mptcp_sock *build_msk(struct kunit *test)
 	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, msk);
 	refcount_set(&((struct sock *)msk)->sk_refcnt, 1);
 	sock_net_set((struct sock *)msk, &init_net);
+
+	/* be sure the token helpers can dereference sk->sk_prot */
+	((struct sock *)msk)->sk_prot = &tcp_prot;
 	return msk;
 }