diff --git a/lib/libc/sys/__vdso_gettimeofday.c b/lib/libc/sys/__vdso_gettimeofday.c
--- a/lib/libc/sys/__vdso_gettimeofday.c
+++ b/lib/libc/sys/__vdso_gettimeofday.c
@@ -32,6 +32,7 @@
 #include <sys/time.h>
 #include <sys/vdso.h>
 #include <errno.h>
+#include <stdbool.h>
 #include <strings.h>
 #include <time.h>
 #include <machine/atomic.h>
@@ -59,7 +60,7 @@
  * is based on the kernel implementation.
  */
 static int
-binuptime(struct bintime *bt, struct vdso_timekeep *tk, int abs)
+binuptime(struct bintime *bt, struct vdso_timekeep *tk, bool abs)
 {
 	struct vdso_timehands *th;
 	uint32_t curr, gen;
@@ -105,6 +106,30 @@
 	return (0);
 }
 
+static int
+getnanouptime(struct bintime *bt, struct vdso_timekeep *tk)
+{
+	struct vdso_timehands *th;
+	uint32_t curr, gen;
+
+	do {
+		if (!tk->tk_enabled)
+			return (ENOSYS);
+
+		curr = atomic_load_acq_32(&tk->tk_current);
+		th = &tk->tk_th[curr];
+		gen = atomic_load_acq_32(&th->th_gen);
+		*bt = th->th_offset;
+
+		/*
+		 * Ensure that the load of th_offset is completed
+		 * before the load of th_gen.
+		 */
+		atomic_thread_fence_acq();
+	} while (curr != tk->tk_current || gen == 0 || gen != th->th_gen);
+	return (0);
+}
+
 static struct vdso_timekeep *tk;
 
 #pragma weak __vdso_gettimeofday
@@ -135,7 +160,7 @@
 __vdso_clock_gettime(clockid_t clock_id, struct timespec *ts)
 {
 	struct bintime bt;
-	int abs, error;
+	int error;
 
 	if (tk == NULL) {
 		error = _elf_aux_info(AT_TIMEKEEP, &tk, sizeof(tk));
@@ -149,20 +174,22 @@
 	case CLOCK_REALTIME_PRECISE:
 	case CLOCK_REALTIME_FAST:
 	case CLOCK_SECOND:
-		abs = 1;
+		error = binuptime(&bt, tk, true);
 		break;
 	case CLOCK_MONOTONIC:
 	case CLOCK_MONOTONIC_PRECISE:
-	case CLOCK_MONOTONIC_FAST:
 	case CLOCK_UPTIME:
 	case CLOCK_UPTIME_PRECISE:
+		error = binuptime(&bt, tk, false);
+		break;
+	case CLOCK_MONOTONIC_FAST:
 	case CLOCK_UPTIME_FAST:
-		abs = 0;
+		error = getnanouptime(&bt, tk);
 		break;
 	default:
-		return (ENOSYS);
+		error = ENOSYS;
+		break;
 	}
-	error = binuptime(&bt, tk, abs);
 	if (error != 0)
 		return (error);
 	bintime2timespec(&bt, ts);