diff --git a/clock.c b/clock.c
index 95abbee5..bee97f8f 100644
--- a/clock.c
+++ b/clock.c
@@ -566,15 +566,51 @@ void ARCH_DEP( fetch_int_timer )( REGS* regs )
 /*  host_ETOD - Primary high-resolution clock fetch and conversion   */
 /*-------------------------------------------------------------------*/
 
+#if defined( __EMSCRIPTEN__ )
+/* Emscripten CLOCK_REALTIME is Date.now() (1 ms resolution), but     */
+/* CLOCK_MONOTONIC is performance.now() (microseconds or better).    */
+/* Use the monotonic clock plus a fixed offset to the epoch, taken   */
+/* one time at the first call. (A browser tab that sleeps keeps the  */
+/* monotonic clock consistent; no host hibernate issue here.)        */
+static pthread_once_t   host_ETOD_once = PTHREAD_ONCE_INIT;
+static struct timespec  host_ETOD_offset;     /* realtime - monotonic */
+
+static void host_ETOD_init( void )
+{
+    struct timespec rt, mono;
+    clock_gettime( CLOCK_REALTIME,  &rt   );
+    clock_gettime( CLOCK_MONOTONIC, &mono );
+    host_ETOD_offset.tv_sec  = rt.tv_sec  - mono.tv_sec;
+    host_ETOD_offset.tv_nsec = rt.tv_nsec - mono.tv_nsec;
+    if (host_ETOD_offset.tv_nsec < 0)
+    {
+        host_ETOD_offset.tv_nsec += 1000000000L;
+        host_ETOD_offset.tv_sec  -= 1;
+    }
+}
+#endif
+
 ETOD* host_ETOD( ETOD* ETOD )
 {
     struct timespec time;
 
+#if defined( __EMSCRIPTEN__ )
+    pthread_once( &host_ETOD_once, host_ETOD_init );
+    clock_gettime( CLOCK_MONOTONIC, &time );
+    time.tv_sec  += host_ETOD_offset.tv_sec;
+    time.tv_nsec += host_ETOD_offset.tv_nsec;
+    if (time.tv_nsec >= 1000000000L)
+    {
+        time.tv_nsec -= 1000000000L;
+        time.tv_sec  += 1;
+    }
+#else
     /* Should use CLOCK_MONOTONIC + adjustment, but host sleep/hibernate
      * destroys consistent monotonic clock.
      */
 
     clock_gettime( CLOCK_REALTIME, &time );
+#endif
     timespec2ETOD( ETOD, &time );
     return ( ETOD );                /* Return address of result      */
 }