diff --git a/libc/include/fcntl.h b/libc/include/fcntl.h
index 6e2ad51..74ea523 100644
--- a/libc/include/fcntl.h
+++ b/libc/include/fcntl.h
@@ -86,6 +86,10 @@
 extern int posix_fadvise64(int, off64_t, off64_t, int);
 extern int posix_fallocate64(int, off64_t, off64_t);
 
+#if defined(__USE_GNU)
+ssize_t readahead(int, off64_t, size_t);
+#endif
+
 extern int __open_2(const char*, int);
 extern int __open_real(const char*, int, ...) __RENAME(open);
 extern int __openat_2(int, const char*, int);
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);
+}