diff --git a/src/lib/libhtml5.js b/src/lib/libhtml5.js
index a9c35d1cd6174..b79b722c7fbfc 100644
--- a/src/lib/libhtml5.js
+++ b/src/lib/libhtml5.js
@@ -822,26 +822,23 @@ var LibraryHTML5 = {
   _emscripten_get_last_deviceorientation_event: () => JSEvents.deviceOrientationEvent,
 
   $fillDeviceMotionEventData: (eventStruct, e, target) => {
+    var a = e.acceleration;
+    var ag = e.accelerationIncludingGravity;
+    var rr = e.rotationRate;
     var supportedFields = 0;
-    var a = e['acceleration'];
     supportedFields |= a && {{{ cDefs.EMSCRIPTEN_DEVICE_MOTION_EVENT_SUPPORTS_ACCELERATION }}};
-    var ag = e['accelerationIncludingGravity'];
     supportedFields |= ag && {{{ cDefs.EMSCRIPTEN_DEVICE_MOTION_EVENT_SUPPORTS_ACCELERATION_INCLUDING_GRAVITY }}};
-    var rr = e['rotationRate'];
     supportedFields |= rr && {{{ cDefs.EMSCRIPTEN_DEVICE_MOTION_EVENT_SUPPORTS_ROTATION_RATE }}};
-    a ??= {};
-    ag ??= {};
-    rr ??= {};
     {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.supportedFields, 'supportedFields', 'i32') }}};
-    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationX, 'a["x"]', 'double') }}};
-    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationY, 'a["y"]', 'double') }}};
-    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationZ, 'a["z"]', 'double') }}};
-    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationIncludingGravityX, 'ag["x"]', 'double') }}};
-    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationIncludingGravityY, 'ag["y"]', 'double') }}};
-    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationIncludingGravityZ, 'ag["z"]', 'double') }}};
-    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.rotationRateAlpha, 'rr["alpha"]', 'double') }}};
-    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.rotationRateBeta, 'rr["beta"]', 'double') }}};
-    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.rotationRateGamma, 'rr["gamma"]', 'double') }}};
+    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationX, 'a?.x', 'double') }}};
+    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationY, 'a?.y', 'double') }}};
+    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationZ, 'a?.z', 'double') }}};
+    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationIncludingGravityX, 'ag?.x', 'double') }}};
+    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationIncludingGravityY, 'ag?.y', 'double') }}};
+    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.accelerationIncludingGravityZ, 'ag?.z', 'double') }}};
+    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.rotationRateAlpha, 'rr?.alpha', 'double') }}};
+    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.rotationRateBeta, 'rr?.beta', 'double') }}};
+    {{{ makeSetValue('eventStruct', C_STRUCTS.EmscriptenDeviceMotionEvent.rotationRateGamma, 'rr?.gamma', 'double') }}};
   },
 
   $registerDeviceMotionEventCallback__noleakcheck: true,
diff --git a/test/codesize/test_codesize_hello_dylink_all.json b/test/codesize/test_codesize_hello_dylink_all.json
index 219eb52db7e3c..a6ae726a6c706 100644
--- a/test/codesize/test_codesize_hello_dylink_all.json
+++ b/test/codesize/test_codesize_hello_dylink_all.json
@@ -1,7 +1,7 @@
 {
-  "a.out.js": 244585,
+  "a.out.js": 244573,
   "a.out.nodebug.wasm": 578054,
-  "total": 822639,
+  "total": 822627,
   "sent": [
     "IMG_Init",
     "IMG_Load",