diff --git a/src/lib/libwebaudio.js b/src/lib/libwebaudio.js
index 113dc0f5b7eba..87eb86c07d56f 100644
--- a/src/lib/libwebaudio.js
+++ b/src/lib/libwebaudio.js
@@ -8,7 +8,7 @@
 #error "-sAUDIO_WORKLET does not support -sSINGLE_FILE"
 #endif
 
-let LibraryWebAudio = {
+var LibraryWebAudio = {
   $EmAudio: {},
   $EmAudioCounter: 0,
 
@@ -54,16 +54,16 @@ let LibraryWebAudio = {
   // this avoids the user needing to manually add the dependency on the command line.
   emscripten_create_audio_context__deps: ['$emscriptenRegisterAudioObject', '$emscriptenGetAudioObject'],
   emscripten_create_audio_context: (options) => {
-    let ctx = window.AudioContext || window.webkitAudioContext;
+    var ctx = window.AudioContext || window.webkitAudioContext;
 #if ASSERTIONS
     if (!ctx) console.error('emscripten_create_audio_context failed! Web Audio is not supported.');
 #endif
     options >>= 2;
 
-    let opts = options ? {
-      latencyHint: HEAPU32[options] ? UTF8ToString(HEAPU32[options]) : void 0,
-      sampleRate: HEAP32[options+1] || void 0
-    } : void 0;
+    var opts = options ? {
+      latencyHint: HEAPU32[options] ? UTF8ToString(HEAPU32[options]) : undefined,
+      sampleRate: HEAP32[options+1] || undefined
+    } : undefined;
 
 #if WEBAUDIO_DEBUG
     console.log(`Creating new WebAudio context with parameters:`);
@@ -146,8 +146,8 @@ let LibraryWebAudio = {
     assert(EmAudio[contextHandle] instanceof (window.AudioContext || window.webkitAudioContext), `Called emscripten_start_wasm_audio_worklet_thread_async() on a context handle ${contextHandle} that is not an AudioContext, but of type ${typeof EmAudio[contextHandle]}`);
 #endif
 
-    let audioContext = EmAudio[contextHandle],
-      audioWorklet = audioContext.audioWorklet;
+    var audioContext = EmAudio[contextHandle];
+    var audioWorklet = audioContext.audioWorklet;
 
 #if ASSERTIONS
     assert(stackLowestAddress != 0, 'AudioWorklets require a dedicated stack space for audio data marshalling between Wasm and JS!');
@@ -162,7 +162,7 @@ let LibraryWebAudio = {
     console.log(`emscripten_start_wasm_audio_worklet_thread_async() adding audioworklet.js...`);
 #endif
 
-    let audioWorkletCreationFailed = () => {
+    var audioWorkletCreationFailed = () => {
 #if ASSERTIONS || WEBAUDIO_DEBUG
       console.error(`emscripten_start_wasm_audio_worklet_thread_async() addModule() failed!`);
 #endif
@@ -208,10 +208,10 @@ let LibraryWebAudio = {
 
   $_EmAudioDispatchProcessorCallback__deps: ['$getWasmTableEntry'],
   $_EmAudioDispatchProcessorCallback: (e) => {
-    let data = e.data;
+    var data = e.data;
     // '_wsc' is short for 'wasm call', trying to use an identifier name that
     // will never conflict with user code
-    let wasmCall = data['_wsc'];
+    var wasmCall = data['_wsc'];
     wasmCall && getWasmTableEntry(wasmCall)(...data.args);
   },
 
@@ -223,7 +223,7 @@ let LibraryWebAudio = {
 #endif
 
     options >>= 2;
-    let audioParams = [],
+    var audioParams = [],
       numAudioParams = HEAPU32[options+1],
       audioParamDescriptors = HEAPU32[options+2] >> 2,
       i = 0;
@@ -265,21 +265,21 @@ let LibraryWebAudio = {
     options >>= 2;
 
     function readChannelCountArray(heapIndex, numOutputs) {
-      let channelCounts = [];
+      var channelCounts = [];
       while (numOutputs--) channelCounts.push(HEAPU32[heapIndex++]);
       return channelCounts;
     }
 
-    let opts = options ? {
+    var opts = options ? {
       numberOfInputs: HEAP32[options],
       numberOfOutputs: HEAP32[options+1],
-      outputChannelCount: HEAPU32[options+2] ? readChannelCountArray(HEAPU32[options+2]>>2, HEAP32[options+1]) : void 0,
+      outputChannelCount: HEAPU32[options+2] ? readChannelCountArray(HEAPU32[options+2]>>2, HEAP32[options+1]) : undefined,
       processorOptions: {
         callback,
         userData,
         samplesPerChannel: emscriptenGetContextQuantumSize(contextHandle),
       }
-    } : void 0;
+    } : undefined;
 
 #if WEBAUDIO_DEBUG
     console.log(`Creating AudioWorkletNode "${UTF8ToString(name)}" on context=${contextHandle} with options:`);
diff --git a/test/code_size/audio_worklet_wasm.js b/test/code_size/audio_worklet_wasm.js
index 80e2b3ab5538c..3ab8a368262e5 100644
--- a/test/code_size/audio_worklet_wasm.js
+++ b/test/code_size/audio_worklet_wasm.js
@@ -135,8 +135,7 @@ var N = [], O = a => {
         if (G[c + 2]) {
             var m = G[c + 2] >> 2;
             c = M[c + 1];
-            let w = [];
-            for (;c--; ) w.push(G[m++]);
+            for (var w = []; c--; ) w.push(G[m++]);
             m = w;
         } else m = void 0;
         d = {
@@ -155,8 +154,7 @@ var N = [], O = a => {
     return T;
 }, da = (a, b, c, d) => {
     b >>= 2;
-    let e = [], h = G[b + 1], f = G[b + 2] >> 2, m = 0;
-    for (;h--; ) e.push({
+    for (var e = [], h = G[b + 1], f = G[b + 2] >> 2, m = 0; h--; ) e.push({
         name: m++,
         defaultValue: I[f++],
         minValue: I[f++],
@@ -175,10 +173,10 @@ var N = [], O = a => {
     });
 }, ea = () => !1, fa = 1, ha = a => {
     a = a.data;
-    let b = a._wsc;
+    var b = a._wsc;
     b && C.get(b)(...a.A);
 }, ia = a => E(a), ja = (a, b, c, d, e) => {
-    let h = S[a], f = h.audioWorklet, m = () => {
+    var h = S[a], f = h.audioWorklet, m = () => {
         C.get(d)(a, 0, e);
     };
     if (!f) return m();
diff --git a/test/code_size/test_minimal_runtime_code_size_audio_worklet.json b/test/code_size/test_minimal_runtime_code_size_audio_worklet.json
index 9648aff3d49a7..914c498e84979 100644
--- a/test/code_size/test_minimal_runtime_code_size_audio_worklet.json
+++ b/test/code_size/test_minimal_runtime_code_size_audio_worklet.json
@@ -1,10 +1,10 @@
 {
   "a.html": 519,
   "a.html.gz": 357,
-  "a.js": 3853,
-  "a.js.gz": 2045,
+  "a.js": 3851,
+  "a.js.gz": 2048,
   "a.wasm": 1288,
   "a.wasm.gz": 860,
-  "total": 5660,
-  "total_gz": 3262
+  "total": 5658,
+  "total_gz": 3265
 }