diff --git a/Makefile b/Makefile
index 50c87ddc6..4a216c3a2 100644
--- a/Makefile
+++ b/Makefile
@@ -125,3 +125,5 @@ endif
 clean:
 	@echo "CLEAN"
 	@rm -f $(products)
+
+-include build/targets.$(PLATFORM).mak
diff --git a/apps/apps_container.cpp b/apps/apps_container.cpp
index 13bc02e13..a8ae4db8e 100644
--- a/apps/apps_container.cpp
+++ b/apps/apps_container.cpp
@@ -136,11 +136,6 @@ void AppsContainer::run() {
   switchTo(nullptr);
 }
 
-void AppsContainer::runWhile(bool (*callback)(void * ctx), void * ctx) {
-  while (callback(ctx) && RunLoop::step()) {
-  }
-}
-
 bool AppsContainer::updateBatteryState() {
   if (m_window.updateBatteryLevel() ||
       m_window.updateIsChargingState() ||
diff --git a/apps/apps_container.h b/apps/apps_container.h
index d7a7b7a56..89126897f 100644
--- a/apps/apps_container.h
+++ b/apps/apps_container.h
@@ -39,7 +39,6 @@ public:
   virtual bool dispatchEvent(Ion::Events::Event event) override;
   void switchTo(App::Snapshot * snapshot) override;
   void run() override;
-  void runWhile(bool (*callback)(void * ctx), void * ctx);
   bool updateBatteryState();
   void refreshPreferences();
   void displayExamModePopUp(bool activate);
diff --git a/build/platform.emscripten.mak b/build/platform.emscripten.mak
index ac856c8ba..3ecd61880 100644
--- a/build/platform.emscripten.mak
+++ b/build/platform.emscripten.mak
@@ -3,14 +3,3 @@ USE_LIBA = 0
 EXE = js
 OS_WITH_ONBOARDING_APP ?= 0
 OS_WITH_SOFTWARE_UPDATE_PROMPT ?= 0
-
-numworks_simulator.zip: LDFLAGS += --memory-init-file 0
-numworks_simulator.zip: app.js
-	@rm -rf $(basename $@)
-	@mkdir $(basename $@)
-	@cp app.js $(basename $@)/firmware.js
-	@cp ion/src/emscripten/background.jpg $(basename $@)/
-	@cp ion/src/emscripten/simulator.html $(basename $@)/
-	@echo "ZIP     $@"
-	@zip -r -9 $@ $(basename $@) > /dev/null
-	@rm -rf $(basename $@)
diff --git a/build/targets.emscripten.mak b/build/targets.emscripten.mak
new file mode 100644
index 000000000..1515c2bbe
--- /dev/null
+++ b/build/targets.emscripten.mak
@@ -0,0 +1,17 @@
+app.js: LDFLAGS += -s 'EMTERPRETIFY_FILE="app.etb"'
+app.js: $(app_objs) $(app_image_objs)
+
+app.packed.js: LDFLAGS += --memory-init-file 0
+app.packed.js: $(app_objs) $(app_image_objs)
+
+numworks_simulator.zip: app.packed.js
+	@rm -rf $(basename $@)
+	@mkdir $(basename $@)
+	@cp app.packed.js $(basename $@)/epsilon.js
+	@cp ion/src/emscripten/background.jpg $(basename $@)/
+	@cp ion/src/emscripten/simulator.html $(basename $@)/
+	@echo "ZIP     $@"
+	@zip -r -9 $@ $(basename $@) > /dev/null
+	@rm -rf $(basename $@)
+
+products += $(addprefix app.,js mem etb) app.packed.js numworks_simulator.zip
diff --git a/build/toolchain.emscripten.mak b/build/toolchain.emscripten.mak
index aeb11453c..fad4d210e 100644
--- a/build/toolchain.emscripten.mak
+++ b/build/toolchain.emscripten.mak
@@ -1,5 +1,6 @@
 CC = emcc
 CXX = emcc
 LD = emcc
-LDFLAGS = -s EXPORTED_FUNCTIONS="['_main', '_IonEventsEmscriptenPushEvent']" -Os
+SFLAGS = -s EMTERPRETIFY=1 -s EMTERPRETIFY_ASYNC=1
+LDFLAGS =  -Oz -s EMTERPRETIFY=1 -s EMTERPRETIFY_ASYNC=1 -s EXPORTED_FUNCTIONS="['_main', '_IonEventsEmscriptenPushEvent']"
 SIZE = size
diff --git a/escher/include/escher/run_loop.h b/escher/include/escher/run_loop.h
index 2788fb2f8..2ef4b9207 100644
--- a/escher/include/escher/run_loop.h
+++ b/escher/include/escher/run_loop.h
@@ -8,12 +8,13 @@ class RunLoop {
 public:
   RunLoop();
   void run();
+  void runWhile(bool (*callback)(void * ctx), void * ctx);
 protected:
   virtual bool dispatchEvent(Ion::Events::Event e) = 0;
   virtual int numberOfTimers();
   virtual Timer * timerAtIndex(int i);
-  bool step();
 private:
+  bool step();
   int m_time;
 };
 
diff --git a/escher/src/run_loop.cpp b/escher/src/run_loop.cpp
index 55eb0d870..c35fcbd6a 100644
--- a/escher/src/run_loop.cpp
+++ b/escher/src/run_loop.cpp
@@ -18,12 +18,12 @@ Timer * RunLoop::timerAtIndex(int i) {
 }
 
 void RunLoop::run() {
-#ifdef __EMSCRIPTEN__
-  emscripten_set_main_loop_arg([](void * ctx){ ((RunLoop *)ctx)->step(); }, this, 0, 1);
-#else
-  while(step()) {
+  runWhile(nullptr, nullptr);
+}
+
+void RunLoop::runWhile(bool (*callback)(void * ctx), void * ctx) {
+  while ((callback == nullptr || callback(ctx)) && step()) {
   }
-#endif
 }
 
 bool RunLoop::step() {
diff --git a/ion/src/emscripten/events_keyboard.cpp b/ion/src/emscripten/events_keyboard.cpp
index 46972ffe8..72fea581c 100644
--- a/ion/src/emscripten/events_keyboard.cpp
+++ b/ion/src/emscripten/events_keyboard.cpp
@@ -4,6 +4,7 @@
 extern "C" {
 #include <SDL/SDL.h>
 }
+#include <emscripten.h>
 
 static Ion::Events::Event sEvent = Ion::Events::None;
 
@@ -47,6 +48,7 @@ static constexpr Event sEventForASCIICharAbove32[95] = {
 
 Event getEvent(int * timeout) {
   Ion::Display::Emscripten::refresh();
+  emscripten_sleep(1);
   if (sEvent != None) {
     Event event = sEvent;
     updateModifiersFromEvent(event);
diff --git a/ion/src/emscripten/simulator.html b/ion/src/emscripten/simulator.html
index 2bcb76a8c..c0d91aaa4 100644
--- a/ion/src/emscripten/simulator.html
+++ b/ion/src/emscripten/simulator.html
@@ -197,7 +197,7 @@ var Module = {
   canvas: document.getElementById("screen")
 };
     </script>
-    <script src="firmware.js"></script>
+    <script src="epsilon.js"></script>
     <script>
 var buttons = document.querySelectorAll(".calculator .keyboard a");
 for (var i=0; i< buttons.length; i++) {