diff --git a/tools/testing/selftests/filesystems/incfs/incfs_test.c b/tools/testing/selftests/filesystems/incfs/incfs_test.c
index 4c30aec3f545..2d2bc933fefc 100644
--- a/tools/testing/selftests/filesystems/incfs/incfs_test.c
+++ b/tools/testing/selftests/filesystems/incfs/incfs_test.c
@@ -4409,6 +4409,7 @@ static int sysfs_test(const char *mount_dir)
 	int fd = -1;
 	int pid = -1;
 	char buffer[32];
+	char *null_buf = NULL;
 	int status;
 	struct incfs_per_uid_read_timeouts purt_set[] = {
 		{
@@ -4437,13 +4438,13 @@ static int sysfs_test(const char *mount_dir)
 	TEST(fd = open(filename, O_RDONLY | O_CLOEXEC), fd != -1);
 	TESTEQUAL(ioctl_test_last_error(cmd_fd, NULL, 0, 0), 0);
 	TESTEQUAL(sysfs_test_value("reads_failed_timed_out", 0), 0);
-	TEST(read(fd, NULL, 1), -1);
+	TESTEQUAL(read(fd, null_buf, 1), -1);
 	TESTEQUAL(ioctl_test_last_error(cmd_fd, &file.id, 0, -ETIME), 0);
 	TESTEQUAL(sysfs_test_value("reads_failed_timed_out", 2), 0);
 
 	TESTEQUAL(emit_test_file_data(mount_dir, &file), 0);
 	TESTEQUAL(sysfs_test_value("reads_failed_hash_verification", 0), 0);
-	TESTEQUAL(read(fd, NULL, 1), -1);
+	TESTEQUAL(read(fd, null_buf, 1), -1);
 	TESTEQUAL(sysfs_test_value("reads_failed_hash_verification", 1), 0);
 	TESTSYSCALL(close(fd));
 	fd = -1;