diff --git a/apps/apps_container.cpp b/apps/apps_container.cpp
index 368818d0c..162be2380 100644
--- a/apps/apps_container.cpp
+++ b/apps/apps_container.cpp
@@ -257,7 +257,7 @@ void AppsContainer::displayExamModePopUp(bool activate) {
 void AppsContainer::shutdownDueToLowBattery() {
   while (Ion::Battery::level() == Ion::Battery::Charge::EMPTY) {
     m_emptyBatteryWindow.redraw(true);
-    Ion::msleep(3000);
+    Ion::mssleep(3000);
     Ion::Power::suspend();
   }
   window()->redraw(true);
diff --git a/build/toolchain.emscripten.mak b/build/toolchain.emscripten.mak
index baabdca9b..de1cc514c 100644
--- a/build/toolchain.emscripten.mak
+++ b/build/toolchain.emscripten.mak
@@ -58,6 +58,8 @@ __ZThn32_N4Code17ConsoleController9inputTextEPKc \
 __ZThn36_N4Code17ConsoleController9inputTextEPKc \
 __ZZN4Code14MenuControllerC1EP9ResponderPNS_11ScriptStoreEP19ButtonRowControllerbEN3__08__invokeEPvS8_ \
 __ZZN4Code14MenuControllerC1EP9ResponderPNS_11ScriptStoreEP19ButtonRowControllerbENK3__0clEPvS8_ \
+_delay_ms \
+_delay_us \
 _do_load \
 _do_load_from_lexer \
 _fun_bc_call \
@@ -71,7 +73,9 @@ _mp_call_function_n_kw \
 _mp_execute_bytecode \
 _mp_hal_input \
 _mp_import_name \
-_mp_parse_compile_execute
+_mp_parse_compile_execute \
+_mssleep \
+_ussleep
 
 EMTERPRETIFY_WHITELIST = $(foreach sym,$(EMSCRIPTEN_ASYNC_SYMBOLS),"$(sym)",)END
 EMFLAGS = -s PRECISE_F32=1 -s EMTERPRETIFY=1 -s EMTERPRETIFY_ASYNC=1 -s EMTERPRETIFY_WHITELIST='[$(EMTERPRETIFY_WHITELIST:,END=)]'
diff --git a/ion/include/ion/timing.h b/ion/include/ion/timing.h
index 60d32d782..a6c6565f0 100644
--- a/ion/include/ion/timing.h
+++ b/ion/include/ion/timing.h
@@ -11,8 +11,8 @@ namespace Ion {
 EXTERNC uint32_t millis();
 EXTERNC uint32_t micros();
 
-EXTERNC void msleep(long ms);
-EXTERNC void usleep(long us);
+EXTERNC void mssleep(long ms);
+EXTERNC void ussleep(long us);
 
 #ifdef __cplusplus
 }
diff --git a/ion/src/blackbox/ion.cpp b/ion/src/blackbox/ion.cpp
index d946ac29b..ba42d685a 100644
--- a/ion/src/blackbox/ion.cpp
+++ b/ion/src/blackbox/ion.cpp
@@ -1,5 +1,5 @@
 #include <stdint.h>
 #include <ion.h>
 
-void Ion::msleep(long ms) {
+void Ion::mssleep(long ms) {
 }
diff --git a/ion/src/device/backlight.cpp b/ion/src/device/backlight.cpp
index ad71b85d1..22bb30d39 100644
--- a/ion/src/device/backlight.cpp
+++ b/ion/src/device/backlight.cpp
@@ -45,12 +45,12 @@ void shutdown() {
 
 void suspend() {
   GPIOC.ODR()->set(6, false);
-  msleep(3); // Might not need to be blocking
+  mssleep(3); // Might not need to be blocking
 }
 
 void resume() {
   GPIOC.ODR()->set(6, true);
-  usleep(50);
+  ussleep(50);
   uint8_t level = sLevel;
   sLevel = 0xF;
   setLevel(level);
@@ -74,9 +74,9 @@ uint8_t level() {
 void sendPulses(int n) {
   for (int i=0; i<n; i++) {
     GPIOC.ODR()->set(6, false);
-    usleep(20);
+    ussleep(20);
     GPIOC.ODR()->set(6, true);
-    usleep(20);
+    ussleep(20);
   }
 }
 
diff --git a/ion/src/device/bench/command/suspend.cpp b/ion/src/device/bench/command/suspend.cpp
index 27666921d..63dd53543 100644
--- a/ion/src/device/bench/command/suspend.cpp
+++ b/ion/src/device/bench/command/suspend.cpp
@@ -12,7 +12,7 @@ void Suspend(const char * input) {
     return;
   }
   reply(sOK);
-  Ion::msleep(100);
+  Ion::mssleep(100);
   Ion::Power::suspend();
 }
 
diff --git a/ion/src/device/console.cpp b/ion/src/device/console.cpp
index 04d824589..05d48e7e9 100644
--- a/ion/src/device/console.cpp
+++ b/ion/src/device/console.cpp
@@ -63,7 +63,7 @@ void shutdown() {
 bool peerConnected() {
   RxPin.group().PUPDR()->setPull(RxPin.pin(), GPIO::PUPDR::Pull::Down);
   RxPin.group().MODER()->setMode(RxPin.pin(), GPIO::MODER::Mode::Input);
-  msleep(1);
+  mssleep(1);
   bool result = RxPin.group().IDR()->get(RxPin.pin());
   RxPin.group().PUPDR()->setPull(RxPin.pin(), GPIO::PUPDR::Pull::None);
   RxPin.group().MODER()->setMode(RxPin.pin(), GPIO::MODER::Mode::AlternateFunction);
diff --git a/ion/src/device/device.cpp b/ion/src/device/device.cpp
index a140a8abc..0ccdca626 100644
--- a/ion/src/device/device.cpp
+++ b/ion/src/device/device.cpp
@@ -24,16 +24,16 @@ extern "C" {
 
 // Public Ion methods
 
-/* TODO: The delay methods 'msleep' and 'usleep' are currently dependent on the
+/* TODO: The delay methods 'mssleep' and 'ussleep' are currently dependent on the
  * optimizations chosen by the compiler. To prevent that and to gain in
  * precision, we could use the controller cycle counter (Systick). */
 
-void Ion::msleep(long ms) {
+void Ion::mssleep(long ms) {
   for (volatile long i=0; i<8852*ms; i++) {
       __asm volatile("nop");
   }
 }
-void Ion::usleep(long us) {
+void Ion::ussleep(long us) {
   for (volatile long i=0; i<9*us; i++) {
     __asm volatile("nop");
   }
diff --git a/ion/src/device/display.cpp b/ion/src/device/display.cpp
index 717231773..65861a604 100644
--- a/ion/src/device/display.cpp
+++ b/ion/src/device/display.cpp
@@ -162,7 +162,7 @@ void initGPIO() {
   TearingEffectPin.group().MODER()->setMode(TearingEffectPin.pin(), GPIO::MODER::Mode::Input);
   TearingEffectPin.group().PUPDR()->setPull(TearingEffectPin.pin(), GPIO::PUPDR::Pull::None);
 
-  msleep(120);
+  mssleep(120);
 }
 
 
@@ -247,10 +247,10 @@ void shutdownFSMC() {
 
 void initPanel() {
   send_command(Command::Reset);
-  msleep(5);
+  mssleep(5);
 
   send_command(Command::SleepOut);
-  msleep(5);
+  mssleep(5);
 
   send_command(Command::PixelFormatSet, 0x05);
   send_command(Command::TearingEffectLineOn, 0x00);
@@ -262,7 +262,7 @@ void initPanel() {
 void shutdownPanel() {
   send_command(Command::DisplayOff);
   send_command(Command::SleepIn);
-  msleep(5);
+  mssleep(5);
 }
 
 void setDrawingArea(KDRect r, Orientation o) {
diff --git a/ion/src/device/events.cpp b/ion/src/device/events.cpp
index 7f1443566..18a63aab1 100644
--- a/ion/src/device/events.cpp
+++ b/ion/src/device/events.cpp
@@ -6,11 +6,11 @@ namespace Events {
 
 static bool sleepWithTimeout(int duration, int * timeout) {
   if (*timeout >= duration) {
-    msleep(duration);
+    mssleep(duration);
     *timeout -= duration;
     return false;
   } else {
-    msleep(*timeout);
+    mssleep(*timeout);
     *timeout = 0;
     return true;
   }
diff --git a/ion/src/device/keyboard.h b/ion/src/device/keyboard.h
index 9d9aa388a..e4495b8fd 100644
--- a/ion/src/device/keyboard.h
+++ b/ion/src/device/keyboard.h
@@ -56,7 +56,7 @@ inline void activateRow(uint8_t row) {
   Device::RowGPIO.ODR()->setBitRange(9, 0, rowState);
 
   // TODO: 100 us seems to work, but wasn't really calculated
-  usleep(100);
+  ussleep(100);
 }
 
 inline bool columnIsActive(uint8_t column) {
diff --git a/ion/src/device/power.cpp b/ion/src/device/power.cpp
index 021d75cc6..860b76480 100644
--- a/ion/src/device/power.cpp
+++ b/ion/src/device/power.cpp
@@ -29,7 +29,7 @@ void Ion::Power::suspend(bool checkIfPowerKeyReleased) {
     /* Update LEDS
      * if the standby mode was stopped due to a "stop charging" event, we wait
      * a while to be sure that the plug state of the USB is up-to-date. */
-    msleep(200);
+    mssleep(200);
     //Ion::LED::setCharging(Ion::USB::isPlugged(), Ion::Battery::isCharging());
 #endif
 
diff --git a/ion/src/emscripten/main.cpp b/ion/src/emscripten/main.cpp
index c753d78af..09f840e87 100644
--- a/ion/src/emscripten/main.cpp
+++ b/ion/src/emscripten/main.cpp
@@ -2,6 +2,7 @@
 #include "display.h"
 #include "events_keyboard.h"
 #include "../../../apps/global_preferences.h"
+#include <emscripten.h>
 
 extern "C" {
 const char * IonSoftwareVersion();
@@ -19,5 +20,10 @@ int main(int argc, char * argv[]) {
   return 0;
 }
 
-void Ion::msleep(long ms) {
+void Ion::mssleep(long ms) {
+  emscripten_sleep(ms);
+}
+
+void Ion::ussleep(long us) {
+  emscripten_sleep(us/1000);
 }
diff --git a/ion/src/simulator/init.cpp b/ion/src/simulator/init.cpp
index d20630b14..61650c045 100644
--- a/ion/src/simulator/init.cpp
+++ b/ion/src/simulator/init.cpp
@@ -104,7 +104,7 @@ Ion::Events::Event Ion::Events::getEvent(int * timeout) {
 
 #include <chrono>
 
-void Ion::msleep(long ms) {
+void Ion::mssleep(long ms) {
   auto start = std::chrono::high_resolution_clock::now();
   while (true) {
     sDisplay->redraw();
diff --git a/python/src/extmod/modutime.c b/python/src/extmod/modutime.c
index 829ba0cd5..254ff3071 100644
--- a/python/src/extmod/modutime.c
+++ b/python/src/extmod/modutime.c
@@ -35,14 +35,14 @@
 void delay_ms(mp_uint_t delay) {
     uint32_t start = millis();
     while (millis() - start < delay && !micropython_port_should_interrupt(true)) {
-      msleep(1);
+      mssleep(1);
     }
 }
 
 void delay_us(mp_uint_t delay) {
     uint32_t start = micros();
     while (micros() - start < delay && !micropython_port_should_interrupt(false)) {
-      usleep(1);
+      ussleep(1);
     }
 }
 
diff --git a/quiz/src/runner.cpp b/quiz/src/runner.cpp
index b3dbd1a32..be0a08c59 100644
--- a/quiz/src/runner.cpp
+++ b/quiz/src/runner.cpp
@@ -39,7 +39,7 @@ static inline void ion_main_inner() {
   quiz_print("ALL TESTS FINISHED");
 #if !QUIZ_USE_CONSOLE
   while (1) {
-    Ion::msleep(1000);
+    Ion::mssleep(1000);
   }
 #endif
 }
@@ -59,7 +59,7 @@ void ion_main(int argc, char * argv[]) {
     quiz_assert(false);
 #if !QUIZ_USE_CONSOLE
     while (1) {
-      Ion::msleep(1000);
+      Ion::mssleep(1000);
     }
 #endif
   }