diff --git a/ports/unix/unix_mphal.c b/ports/unix/unix_mphal.c
index f43067f646..3fe2fa9fec 100644
--- a/ports/unix/unix_mphal.c
+++ b/ports/unix/unix_mphal.c
@@ -216,6 +216,7 @@ mp_uint_t mp_hal_ticks_us(void) {
 }
 
 uint64_t mp_hal_time_ns(void) {
-    time_t now = time(NULL);
-    return (uint64_t)now * 1000000000ULL;
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    return (uint64_t)tv.tv_sec * 1000000000ULL + (uint64_t)tv.tv_usec * 1000ULL;
 }
diff --git a/ports/windows/windows_mphal.c b/ports/windows/windows_mphal.c
index 8ed087358f..b442b59147 100644
--- a/ports/windows/windows_mphal.c
+++ b/ports/windows/windows_mphal.c
@@ -255,3 +255,9 @@ mp_uint_t mp_hal_ticks_cpu(void) {
     return value.LowPart;
     #endif
 }
+
+uint64_t mp_hal_time_ns(void) {
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    return (uint64_t)tv.tv_sec * 1000000000ULL + (uint64_t)tv.tv_usec * 1000ULL;
+}