diff --git a/extmod/vfs_fat.c b/extmod/vfs_fat.c
index ace5ba5b65..95b7ad9944 100644
--- a/extmod/vfs_fat.c
+++ b/extmod/vfs_fat.c
@@ -311,7 +311,7 @@ STATIC mp_obj_t fat_vfs_stat(mp_obj_t vfs_in, mp_obj_t path_in) {
     } else {
         mode |= MP_S_IFREG;
     }
-    mp_int_t seconds = timeutils_seconds_since_2000(
+    mp_int_t seconds = timeutils_seconds_since_epoch(
         1980 + ((fno.fdate >> 9) & 0x7f),
         (fno.fdate >> 5) & 0x0f,
         fno.fdate & 0x1f,
@@ -319,9 +319,6 @@ STATIC mp_obj_t fat_vfs_stat(mp_obj_t vfs_in, mp_obj_t path_in) {
         (fno.ftime >> 5) & 0x3f,
         2 * (fno.ftime & 0x1f)
         );
-    #if MICROPY_EPOCH_IS_1970
-    seconds += TIMEUTILS_SECONDS_1970_TO_2000;
-    #endif
     t->items[0] = MP_OBJ_NEW_SMALL_INT(mode); // st_mode
     t->items[1] = MP_OBJ_NEW_SMALL_INT(0); // st_ino
     t->items[2] = MP_OBJ_NEW_SMALL_INT(0); // st_dev
diff --git a/extmod/vfs_lfs.c b/extmod/vfs_lfs.c
index a53f66f2d6..9cf3eb1108 100644
--- a/extmod/vfs_lfs.c
+++ b/extmod/vfs_lfs.c
@@ -26,6 +26,7 @@
 
 #include "py/runtime.h"
 #include "py/mphal.h"
+#include "lib/timeutils/timeutils.h"
 #include "extmod/vfs.h"
 #include "extmod/vfs_lfs.h"
 
@@ -126,7 +127,8 @@ const char *mp_vfs_lfs2_make_path(mp_obj_vfs_lfs2_t *self, mp_obj_t path_in);
 mp_obj_t mp_vfs_lfs2_file_open(mp_obj_t self_in, mp_obj_t path_in, mp_obj_t mode_in);
 
 STATIC void lfs_get_mtime(uint8_t buf[8]) {
-    uint64_t ns = mp_hal_time_ns();
+    // On-disk storage of timestamps uses 1970 as the Epoch, so convert from host's Epoch.
+    uint64_t ns = timeutils_nanoseconds_since_epoch_to_nanoseconds_since_1970(mp_hal_time_ns());
     // Store "ns" to "buf" in little-endian format (essentially htole64).
     for (size_t i = 0; i < 8; ++i) {
         buf[i] = ns;
diff --git a/extmod/vfs_lfsx.c b/extmod/vfs_lfsx.c
index d00df53104..35d5f03c59 100644
--- a/extmod/vfs_lfsx.c
+++ b/extmod/vfs_lfsx.c
@@ -365,10 +365,8 @@ STATIC mp_obj_t MP_VFS_LFSx(stat)(mp_obj_t self_in, mp_obj_t path_in) {
         for (size_t i = sizeof(mtime_buf); i > 0; --i) {
             ns = ns << 8 | mtime_buf[i - 1];
         }
-        mtime = timeutils_seconds_since_2000_from_nanoseconds_since_1970(ns);
-        #if MICROPY_EPOCH_IS_1970
-        mtime += TIMEUTILS_SECONDS_1970_TO_2000;
-        #endif
+        // On-disk storage of timestamps uses 1970 as the Epoch, so convert to host's Epoch.
+        mtime = timeutils_seconds_since_epoch_from_nanoseconds_since_1970(ns);
     }
     #endif
 
diff --git a/lib/timeutils/timeutils.h b/lib/timeutils/timeutils.h
index 08b0dc2e85..14da831dc8 100644
--- a/lib/timeutils/timeutils.h
+++ b/lib/timeutils/timeutils.h
@@ -42,14 +42,6 @@ typedef struct _timeutils_struct_time_t {
     uint16_t tm_yday;       // 1..366
 } timeutils_struct_time_t;
 
-static inline uint64_t timeutils_seconds_since_2000_to_nanoseconds_since_1970(mp_uint_t s) {
-    return ((uint64_t)s + TIMEUTILS_SECONDS_1970_TO_2000) * 1000000000ULL;
-}
-
-static inline mp_uint_t timeutils_seconds_since_2000_from_nanoseconds_since_1970(uint64_t ns) {
-    return ns / 1000000000ULL - TIMEUTILS_SECONDS_1970_TO_2000;
-}
-
 bool timeutils_is_leap_year(mp_uint_t year);
 mp_uint_t timeutils_days_in_month(mp_uint_t year, mp_uint_t month);
 mp_uint_t timeutils_year_day(mp_uint_t year, mp_uint_t month, mp_uint_t date);
@@ -63,10 +55,39 @@ mp_uint_t timeutils_seconds_since_2000(mp_uint_t year, mp_uint_t month,
 mp_uint_t timeutils_mktime(mp_uint_t year, mp_int_t month, mp_int_t mday,
     mp_int_t hours, mp_int_t minutes, mp_int_t seconds);
 
-static inline uint64_t timeutils_nanoseconds_since_1970(mp_uint_t year, mp_uint_t month,
+// Select the Epoch used by the port.
+#if MICROPY_EPOCH_IS_1970
+
+static inline uint64_t timeutils_seconds_since_epoch(mp_uint_t year, mp_uint_t month,
     mp_uint_t date, mp_uint_t hour, mp_uint_t minute, mp_uint_t second) {
-    return timeutils_seconds_since_2000_to_nanoseconds_since_1970(
-        timeutils_seconds_since_2000(year, month, date, hour, minute, second));
+    return timeutils_seconds_since_2000(year, month, date, hour, minute, second) + TIMEUTILS_SECONDS_1970_TO_2000;
 }
 
+static inline mp_uint_t timeutils_seconds_since_epoch_from_nanoseconds_since_1970(uint64_t ns) {
+    return ns / 1000000000ULL;
+}
+
+static inline uint64_t timeutils_nanoseconds_since_epoch_to_nanoseconds_since_1970(uint64_t ns) {
+    return ns;
+}
+
+#else // Epoch is 2000
+
+#define timeutils_seconds_since_epoch_to_struct_time timeutils_seconds_since_2000_to_struct_time
+#define timeutils_seconds_since_epoch timeutils_seconds_since_2000
+
+static inline uint64_t timeutils_seconds_since_epoch_to_nanoseconds_since_1970(mp_uint_t s) {
+    return ((uint64_t)s + TIMEUTILS_SECONDS_1970_TO_2000) * 1000000000ULL;
+}
+
+static inline mp_uint_t timeutils_seconds_since_epoch_from_nanoseconds_since_1970(uint64_t ns) {
+    return ns / 1000000000ULL - TIMEUTILS_SECONDS_1970_TO_2000;
+}
+
+static inline int64_t timeutils_nanoseconds_since_epoch_to_nanoseconds_since_1970(int64_t ns) {
+    return ns + TIMEUTILS_SECONDS_1970_TO_2000 * 1000000000ULL;
+}
+
+#endif
+
 #endif // MICROPY_INCLUDED_LIB_TIMEUTILS_TIMEUTILS_H
diff --git a/ports/esp32/fatfs_port.c b/ports/esp32/fatfs_port.c
index 779ba1c88a..cfc52853d0 100644
--- a/ports/esp32/fatfs_port.c
+++ b/ports/esp32/fatfs_port.c
@@ -34,7 +34,7 @@ DWORD get_fattime(void) {
     struct timeval tv;
     gettimeofday(&tv, NULL);
     timeutils_struct_time_t tm;
-    timeutils_seconds_since_2000_to_struct_time(tv.tv_sec, &tm);
+    timeutils_seconds_since_epoch_to_struct_time(tv.tv_sec, &tm);
 
     return ((DWORD)(tm.tm_year - 1980) << 25) | ((DWORD)tm.tm_mon << 21) | ((DWORD)tm.tm_mday << 16) |
            ((DWORD)tm.tm_hour << 11) | ((DWORD)tm.tm_min << 5) | ((DWORD)tm.tm_sec >> 1);
diff --git a/ports/esp32/machine_rtc.c b/ports/esp32/machine_rtc.c
index c776eaa8d3..6902ce85fd 100644
--- a/ports/esp32/machine_rtc.c
+++ b/ports/esp32/machine_rtc.c
@@ -93,7 +93,7 @@ STATIC mp_obj_t machine_rtc_datetime_helper(mp_uint_t n_args, const mp_obj_t *ar
         gettimeofday(&tv, NULL);
         timeutils_struct_time_t tm;
 
-        timeutils_seconds_since_2000_to_struct_time(tv.tv_sec, &tm);
+        timeutils_seconds_since_epoch_to_struct_time(tv.tv_sec, &tm);
 
         mp_obj_t tuple[8] = {
             mp_obj_new_int(tm.tm_year),
@@ -114,7 +114,7 @@ STATIC mp_obj_t machine_rtc_datetime_helper(mp_uint_t n_args, const mp_obj_t *ar
         mp_obj_get_array_fixed_n(args[1], 8, &items);
 
         struct timeval tv = {0};
-        tv.tv_sec = timeutils_seconds_since_2000(mp_obj_get_int(items[0]), mp_obj_get_int(items[1]), mp_obj_get_int(items[2]), mp_obj_get_int(items[4]), mp_obj_get_int(items[5]), mp_obj_get_int(items[6]));
+        tv.tv_sec = timeutils_seconds_since_epoch(mp_obj_get_int(items[0]), mp_obj_get_int(items[1]), mp_obj_get_int(items[2]), mp_obj_get_int(items[4]), mp_obj_get_int(items[5]), mp_obj_get_int(items[6]));
         tv.tv_usec = mp_obj_get_int(items[7]);
         settimeofday(&tv, NULL);
 
diff --git a/ports/esp32/modutime.c b/ports/esp32/modutime.c
index 1f93ce6c30..ac3edb4e9b 100644
--- a/ports/esp32/modutime.c
+++ b/ports/esp32/modutime.c
@@ -44,7 +44,7 @@ STATIC mp_obj_t time_localtime(size_t n_args, const mp_obj_t *args) {
     } else {
         seconds = mp_obj_get_int(args[0]);
     }
-    timeutils_seconds_since_2000_to_struct_time(seconds, &tm);
+    timeutils_seconds_since_epoch_to_struct_time(seconds, &tm);
     mp_obj_t tuple[8] = {
         tuple[0] = mp_obj_new_int(tm.tm_year),
         tuple[1] = mp_obj_new_int(tm.tm_mon),
diff --git a/ports/esp32/mphalport.c b/ports/esp32/mphalport.c
index 3a46edf1f7..ad571bf961 100644
--- a/ports/esp32/mphalport.c
+++ b/ports/esp32/mphalport.c
@@ -200,8 +200,7 @@ void mp_hal_delay_us(uint32_t us) {
 uint64_t mp_hal_time_ns(void) {
     struct timeval tv;
     gettimeofday(&tv, NULL);
-    // gettimeofday returns seconds since 2000/1/1
-    uint64_t ns = timeutils_seconds_since_2000_to_nanoseconds_since_1970(tv.tv_sec);
+    uint64_t ns = tv.tv_sec * 1000000000ULL;
     ns += (uint64_t)tv.tv_usec * 1000ULL;
     return ns;
 }
diff --git a/ports/esp8266/esp_mphal.c b/ports/esp8266/esp_mphal.c
index 9e1b72e438..54f9611e56 100644
--- a/ports/esp8266/esp_mphal.c
+++ b/ports/esp8266/esp_mphal.c
@@ -139,7 +139,7 @@ void MP_FASTCODE(mp_hal_delay_ms)(uint32_t delay) {
 }
 
 uint64_t mp_hal_time_ns(void) {
-    return pyb_rtc_get_us_since_2000() * 1000ULL;
+    return pyb_rtc_get_us_since_epoch() * 1000ULL;
 }
 
 void ets_event_poll(void) {
diff --git a/ports/esp8266/fatfs_port.c b/ports/esp8266/fatfs_port.c
index 8cef0acec3..bbd1051935 100644
--- a/ports/esp8266/fatfs_port.c
+++ b/ports/esp8266/fatfs_port.c
@@ -33,10 +33,10 @@ DWORD get_fattime(void) {
 
     // TODO: Optimize division (there's no HW division support on ESP8266,
     // so it's expensive).
-    uint32_t secs = (uint32_t)(pyb_rtc_get_us_since_2000() / 1000000);
+    uint32_t secs = (uint32_t)(pyb_rtc_get_us_since_epoch() / 1000000);
 
     timeutils_struct_time_t tm;
-    timeutils_seconds_since_2000_to_struct_time(secs, &tm);
+    timeutils_seconds_since_epoch_to_struct_time(secs, &tm);
 
     return ((DWORD)(tm.tm_year - 1980) << 25) | ((DWORD)tm.tm_mon << 21) | ((DWORD)tm.tm_mday << 16) |
            ((DWORD)tm.tm_hour << 11) | ((DWORD)tm.tm_min << 5) | ((DWORD)tm.tm_sec >> 1);
diff --git a/ports/esp8266/machine_rtc.c b/ports/esp8266/machine_rtc.c
index 1aa73f9b31..e7b750fd92 100644
--- a/ports/esp8266/machine_rtc.c
+++ b/ports/esp8266/machine_rtc.c
@@ -84,7 +84,7 @@ STATIC mp_obj_t pyb_rtc_make_new(const mp_obj_type_t *type, size_t n_args, size_
     return (mp_obj_t)&pyb_rtc_obj;
 }
 
-void pyb_rtc_set_us_since_2000(uint64_t nowus) {
+void pyb_rtc_set_us_since_epoch(uint64_t nowus) {
     uint32_t cal = system_rtc_clock_cali_proc();
     // Save RTC ticks for overflow detection.
     rtc_last_ticks = system_get_rtc_time();
@@ -96,7 +96,7 @@ void pyb_rtc_set_us_since_2000(uint64_t nowus) {
     system_rtc_mem_write(MEM_DELTA_ADDR, &delta, sizeof(delta));
 };
 
-uint64_t pyb_rtc_get_us_since_2000() {
+uint64_t pyb_rtc_get_us_since_epoch() {
     uint32_t cal;
     int64_t delta;
     uint32_t rtc_ticks;
@@ -120,17 +120,17 @@ uint64_t pyb_rtc_get_us_since_2000() {
 
 void rtc_prepare_deepsleep(uint64_t sleep_us) {
     // RTC time will reset at wake up. Let's be preared for this.
-    int64_t delta = pyb_rtc_get_us_since_2000() + sleep_us;
+    int64_t delta = pyb_rtc_get_us_since_epoch() + sleep_us;
     system_rtc_mem_write(MEM_DELTA_ADDR, &delta, sizeof(delta));
 }
 
 STATIC mp_obj_t pyb_rtc_datetime(size_t n_args, const mp_obj_t *args) {
     if (n_args == 1) {
         // Get time
-        uint64_t msecs = pyb_rtc_get_us_since_2000() / 1000;
+        uint64_t msecs = pyb_rtc_get_us_since_epoch() / 1000;
 
         timeutils_struct_time_t tm;
-        timeutils_seconds_since_2000_to_struct_time(msecs / 1000, &tm);
+        timeutils_seconds_since_epoch_to_struct_time(msecs / 1000, &tm);
 
         mp_obj_t tuple[8] = {
             mp_obj_new_int(tm.tm_year),
@@ -149,8 +149,8 @@ STATIC mp_obj_t pyb_rtc_datetime(size_t n_args, const mp_obj_t *args) {
         mp_obj_t *items;
         mp_obj_get_array_fixed_n(args[1], 8, &items);
 
-        pyb_rtc_set_us_since_2000(
-            ((uint64_t)timeutils_seconds_since_2000(
+        pyb_rtc_set_us_since_epoch(
+            ((uint64_t)timeutils_seconds_since_epoch(
                 mp_obj_get_int(items[0]),
                 mp_obj_get_int(items[1]),
                 mp_obj_get_int(items[2]),
@@ -209,7 +209,7 @@ STATIC mp_obj_t pyb_rtc_alarm(mp_obj_t self_in, mp_obj_t alarm_id, mp_obj_t time
     }
 
     // set expiry time (in microseconds)
-    pyb_rtc_alarm0_expiry = pyb_rtc_get_us_since_2000() + (uint64_t)mp_obj_get_int(time_in) * 1000;
+    pyb_rtc_alarm0_expiry = pyb_rtc_get_us_since_epoch() + (uint64_t)mp_obj_get_int(time_in) * 1000;
 
     return mp_const_none;
 
@@ -222,7 +222,7 @@ STATIC mp_obj_t pyb_rtc_alarm_left(size_t n_args, const mp_obj_t *args) {
         mp_raise_ValueError(MP_ERROR_TEXT("invalid alarm"));
     }
 
-    uint64_t now = pyb_rtc_get_us_since_2000();
+    uint64_t now = pyb_rtc_get_us_since_epoch();
     if (pyb_rtc_alarm0_expiry <= now) {
         return MP_OBJ_NEW_SMALL_INT(0);
     } else {
diff --git a/ports/esp8266/modmachine.c b/ports/esp8266/modmachine.c
index bc838b4206..cb28d5b144 100644
--- a/ports/esp8266/modmachine.c
+++ b/ports/esp8266/modmachine.c
@@ -132,7 +132,7 @@ STATIC mp_obj_t machine_deepsleep(size_t n_args, const mp_obj_t *args) {
 
     // see if RTC.ALARM0 should wake the device
     if (pyb_rtc_alarm0_wake & MACHINE_WAKE_DEEPSLEEP) {
-        uint64_t t = pyb_rtc_get_us_since_2000();
+        uint64_t t = pyb_rtc_get_us_since_epoch();
         if (pyb_rtc_alarm0_expiry <= t) {
             sleep_us = 1; // alarm already expired so wake immediately
         } else {
diff --git a/ports/esp8266/modmachine.h b/ports/esp8266/modmachine.h
index f5cfc0fa2c..be4debd335 100644
--- a/ports/esp8266/modmachine.h
+++ b/ports/esp8266/modmachine.h
@@ -32,8 +32,8 @@ void pin_set(uint pin, int value);
 extern uint32_t pyb_rtc_alarm0_wake;
 extern uint64_t pyb_rtc_alarm0_expiry;
 
-void pyb_rtc_set_us_since_2000(uint64_t nowus);
-uint64_t pyb_rtc_get_us_since_2000();
+void pyb_rtc_set_us_since_epoch(uint64_t nowus);
+uint64_t pyb_rtc_get_us_since_epoch();
 void rtc_prepare_deepsleep(uint64_t sleep_us);
 
 #endif // MICROPY_INCLUDED_ESP8266_MODMACHINE_H
diff --git a/ports/esp8266/modutime.c b/ports/esp8266/modutime.c
index a951f8f8d2..86534722c7 100644
--- a/ports/esp8266/modutime.c
+++ b/ports/esp8266/modutime.c
@@ -58,11 +58,11 @@ STATIC mp_obj_t time_localtime(size_t n_args, const mp_obj_t *args) {
     timeutils_struct_time_t tm;
     mp_int_t seconds;
     if (n_args == 0 || args[0] == mp_const_none) {
-        seconds = pyb_rtc_get_us_since_2000() / 1000 / 1000;
+        seconds = pyb_rtc_get_us_since_epoch() / 1000 / 1000;
     } else {
         seconds = mp_obj_get_int(args[0]);
     }
-    timeutils_seconds_since_2000_to_struct_time(seconds, &tm);
+    timeutils_seconds_since_epoch_to_struct_time(seconds, &tm);
     mp_obj_t tuple[8] = {
         tuple[0] = mp_obj_new_int(tm.tm_year),
         tuple[1] = mp_obj_new_int(tm.tm_mon),
@@ -98,10 +98,10 @@ STATIC mp_obj_t time_mktime(mp_obj_t tuple) {
 MP_DEFINE_CONST_FUN_OBJ_1(time_mktime_obj, time_mktime);
 
 /// \function time()
-/// Returns the number of seconds, as an integer, since 1/1/2000.
+/// Returns the number of seconds, as an integer, since the Epoch.
 STATIC mp_obj_t time_time(void) {
     // get date and time
-    return mp_obj_new_int(pyb_rtc_get_us_since_2000() / 1000 / 1000);
+    return mp_obj_new_int(pyb_rtc_get_us_since_epoch() / 1000 / 1000);
 }
 MP_DEFINE_CONST_FUN_OBJ_0(time_time_obj, time_time);
 
diff --git a/ports/stm32/modutime.c b/ports/stm32/modutime.c
index 9641ddb473..2a37a130df 100644
--- a/ports/stm32/modutime.c
+++ b/ports/stm32/modutime.c
@@ -76,7 +76,7 @@ STATIC mp_obj_t time_localtime(size_t n_args, const mp_obj_t *args) {
     } else {
         mp_int_t seconds = mp_obj_get_int(args[0]);
         timeutils_struct_time_t tm;
-        timeutils_seconds_since_2000_to_struct_time(seconds, &tm);
+        timeutils_seconds_since_epoch_to_struct_time(seconds, &tm);
         mp_obj_t tuple[8] = {
             tuple[0] = mp_obj_new_int(tm.tm_year),
             tuple[1] = mp_obj_new_int(tm.tm_mon),
@@ -125,7 +125,7 @@ STATIC mp_obj_t time_time(void) {
     RTC_TimeTypeDef time;
     HAL_RTC_GetTime(&RTCHandle, &time, RTC_FORMAT_BIN);
     HAL_RTC_GetDate(&RTCHandle, &date, RTC_FORMAT_BIN);
-    return mp_obj_new_int(timeutils_seconds_since_2000(2000 + date.Year, date.Month, date.Date, time.Hours, time.Minutes, time.Seconds));
+    return mp_obj_new_int(timeutils_seconds_since_epoch(2000 + date.Year, date.Month, date.Date, time.Hours, time.Minutes, time.Seconds));
 }
 MP_DEFINE_CONST_FUN_OBJ_0(time_time_obj, time_time);
 
diff --git a/ports/stm32/rtc.c b/ports/stm32/rtc.c
index 4f759c4bc7..18ecf77505 100644
--- a/ports/stm32/rtc.c
+++ b/ports/stm32/rtc.c
@@ -452,8 +452,8 @@ uint64_t mp_hal_time_ns(void) {
     RTC_DateTypeDef date;
     HAL_RTC_GetTime(&RTCHandle, &time, RTC_FORMAT_BIN);
     HAL_RTC_GetDate(&RTCHandle, &date, RTC_FORMAT_BIN);
-    ns = timeutils_nanoseconds_since_1970(
-        2000 + date.Year, date.Month, date.Date, time.Hours, time.Minutes, time.Seconds);
+    ns = timeutils_seconds_since_epoch(2000 + date.Year, date.Month, date.Date, time.Hours, time.Minutes, time.Seconds);
+    ns *= 1000000000ULL;
     uint32_t usec = ((RTC_SYNCH_PREDIV - time.SubSeconds) * (1000000 / 64)) / ((RTC_SYNCH_PREDIV + 1) / 64);
     ns += usec * 1000;
     #endif
diff --git a/py/mphal.h b/py/mphal.h
index 6d11f6ddc0..0d4b1224e5 100644
--- a/py/mphal.h
+++ b/py/mphal.h
@@ -76,7 +76,7 @@ mp_uint_t mp_hal_ticks_cpu(void);
 #endif
 
 #ifndef mp_hal_time_ns
-// Nanoseconds since 1970/1/1.
+// Nanoseconds since the Epoch.
 uint64_t mp_hal_time_ns(void);
 #endif