diff --git a/tools/testing/selftests/bpf/prog_tests/check_mtu.c b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
index 5338d2ea0460..2a9a30650350 100644
--- a/tools/testing/selftests/bpf/prog_tests/check_mtu.c
+++ b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
@@ -183,7 +183,7 @@ static void test_check_mtu_tc(__u32 mtu, __u32 ifindex)
 
 void serial_test_check_mtu(void)
 {
-	__u32 mtu_lo;
+	int mtu_lo;
 
 	if (test__start_subtest("bpf_check_mtu XDP-attach"))
 		test_check_mtu_xdp_attach();