diff --git a/tests/unistd_test.cpp b/tests/unistd_test.cpp
index 9969d49..f50c102 100644
--- a/tests/unistd_test.cpp
+++ b/tests/unistd_test.cpp
@@ -112,3 +112,7 @@
   ASSERT_EQ(-1, read(-1, buf, sizeof(buf)));
   ASSERT_EQ(EBADF, errno);
 }
+
+TEST(unistd, alarm) {
+  ASSERT_EQ(0U, alarm(0));
+}