diff --git a/src/header/time/mod.rs b/src/header/time/mod.rs
index 1a432bf3..db30e0d7 100644
--- a/src/header/time/mod.rs
+++ b/src/header/time/mod.rs
@@ -7,7 +7,7 @@ use crate::{
     error::{Errno, ResultExt},
     header::{
         bits_timespec::timespec,
-        errno::{EFAULT, ENOMEM, EOVERFLOW, ETIMEDOUT},
+        errno::{EFAULT, EINVAL, ENOMEM, EOVERFLOW, ETIMEDOUT},
         signal::sigevent,
         stdlib::getenv,
         unistd::readlink,
@@ -280,7 +280,19 @@ pub extern "C" fn clock_nanosleep(
     rqtp: *const timespec,
     rmtp: *mut timespec,
 ) -> c_int {
-    unimplemented!();
+    match clock_id {
+        CLOCK_REALTIME | CLOCK_MONOTONIC => {
+            if flags == TIMER_ABSTIME {
+                return EINVAL;
+            }
+            match unsafe { Sys::nanosleep(rqtp, rmtp) } {
+                Ok(()) => 0,
+                Err(Errno(ETIMEDOUT)) => ETIMEDOUT,
+                Err(Errno(e)) => e,
+            }
+        }
+        _ => EINVAL,
+    }
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/clock_getres.html>.