diff --git a/libc/include/sys/linux-syscalls.h b/libc/include/sys/linux-syscalls.h
index 7b74a4b..2fa5d3a 100644
--- a/libc/include/sys/linux-syscalls.h
+++ b/libc/include/sys/linux-syscalls.h
@@ -20,6 +20,7 @@
 #define __NR_getresuid32                  (__NR_SYSCALL_BASE + 209)
 #define __NR_getresgid32                  (__NR_SYSCALL_BASE + 211)
 #define __NR_gettid                       (__NR_SYSCALL_BASE + 224)
+#define __NR_readahead                    (__NR_SYSCALL_BASE + 225)
 #define __NR_getgroups32                  (__NR_SYSCALL_BASE + 205)
 #define __NR_getpgid                      (__NR_SYSCALL_BASE + 132)
 #define __NR_getppid                      (__NR_SYSCALL_BASE + 64)
diff --git a/libc/include/sys/linux-unistd.h b/libc/include/sys/linux-unistd.h
index ae9077f..f060374 100644
--- a/libc/include/sys/linux-unistd.h
+++ b/libc/include/sys/linux-unistd.h
@@ -20,6 +20,7 @@
 uid_t            getresuid (void);
 gid_t            getresgid (void);
 pid_t            gettid (void);
+ssize_t          readahead (int, off64_t, size_t);
 int              getgroups (int, gid_t *);
 pid_t            getpgid (pid_t);
 pid_t            getppid (void);