diff --git a/libc/include/machine/posix_limits.h b/libc/include/machine/posix_limits.h
index e5a299b..939a1de 100644
--- a/libc/include/machine/posix_limits.h
+++ b/libc/include/machine/posix_limits.h
@@ -41,7 +41,7 @@
 #define _POSIX_CHILD_MAX            25
 #define _POSIX_CHOWN_RESTRICTED     1  /* yes, chown requires appropriate privileges */
 #define _POSIX_CLOCK_SELECTION      200809L
-#define _POSIX_CPUTIME              -1  /* clock_getcpuclockid() not implemented */
+#define _POSIX_CPUTIME              200809L
 #define _POSIX_DELAYTIMER_MAX       32
 #define _POSIX_FSYNC                200809L  /* fdatasync() supported */
 #define _POSIX_HOST_NAME_MAX        255
diff --git a/libc/include/time.h b/libc/include/time.h
index e34eb34..1b0f6a1 100644
--- a/libc/include/time.h
+++ b/libc/include/time.h
@@ -85,6 +85,8 @@
 
 extern clock_t clock(void) __LIBC_ABI_PUBLIC__;
 
+extern int clock_getcpuclockid(pid_t, clockid_t*) __LIBC_ABI_PUBLIC__;
+
 extern int clock_getres(clockid_t, struct timespec*) __LIBC_ABI_PUBLIC__;
 extern int clock_gettime(clockid_t, struct timespec*) __LIBC_ABI_PUBLIC__;
 extern int clock_nanosleep(clockid_t, int, const struct timespec*, struct timespec*) __LIBC_ABI_PUBLIC__;