diff --git a/tests/fcntl_test.cpp b/tests/fcntl_test.cpp
index 3fd0a8c..212cce6 100644
--- a/tests/fcntl_test.cpp
+++ b/tests/fcntl_test.cpp
@@ -237,3 +237,10 @@
   ASSERT_STREQ(expected, buf1);
   ASSERT_STREQ(expected, buf2);
 }
+
+TEST(fcntl, readahead) {
+  // Just check that the function is available.
+  errno = 0;
+  ASSERT_EQ(-1, readahead(-1, 0, 123));
+  ASSERT_EQ(EBADF, errno);
+}