diff --git a/ext/bg/search.html b/ext/bg/search.html
index 7e163865..f18bed0d 100644
--- a/ext/bg/search.html
+++ b/ext/bg/search.html
@@ -89,6 +89,7 @@
         <script src="/mixed/js/scroll.js"></script>
         <script src="/mixed/js/text-scanner.js"></script>
         <script src="/mixed/js/template-handler.js"></script>
+        <script src="/mixed/js/text-to-speech-audio.js"></script>
 
         <script src="/bg/js/query-parser-generator.js"></script>
         <script src="/bg/js/query-parser.js"></script>
diff --git a/ext/bg/settings.html b/ext/bg/settings.html
index b01fbf73..5ee23785 100644
--- a/ext/bg/settings.html
+++ b/ext/bg/settings.html
@@ -1172,6 +1172,7 @@
         <script src="/mixed/js/dom-data-binder.js"></script>
         <script src="/mixed/js/object-property-accessor.js"></script>
         <script src="/mixed/js/task-accumulator.js"></script>
+        <script src="/mixed/js/text-to-speech-audio.js"></script>
 
         <script src="/bg/js/anki.js"></script>
         <script src="/bg/js/anki-note-builder.js"></script>
diff --git a/ext/fg/float.html b/ext/fg/float.html
index bd2508e6..725b7d8b 100644
--- a/ext/fg/float.html
+++ b/ext/fg/float.html
@@ -64,6 +64,7 @@
         <script src="/mixed/js/scroll.js"></script>
         <script src="/mixed/js/text-scanner.js"></script>
         <script src="/mixed/js/template-handler.js"></script>
+        <script src="/mixed/js/text-to-speech-audio.js"></script>
 
         <script src="/bg/js/query-parser-generator.js"></script>
         <script src="/bg/js/query-parser.js"></script>
diff --git a/ext/mixed/js/audio-system.js b/ext/mixed/js/audio-system.js
index 4a49c135..a8226820 100644
--- a/ext/mixed/js/audio-system.js
+++ b/ext/mixed/js/audio-system.js
@@ -15,55 +15,9 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-class TextToSpeechAudio {
-    constructor(text, voice) {
-        this.text = text;
-        this.voice = voice;
-        this._utterance = null;
-        this._volume = 1;
-    }
-
-    get currentTime() {
-        return 0;
-    }
-    set currentTime(value) {
-        // NOP
-    }
-
-    get volume() {
-        return this._volume;
-    }
-    set volume(value) {
-        this._volume = value;
-        if (this._utterance !== null) {
-            this._utterance.volume = value;
-        }
-    }
-
-    async play() {
-        try {
-            if (this._utterance === null) {
-                this._utterance = new SpeechSynthesisUtterance(this.text || '');
-                this._utterance.lang = 'ja-JP';
-                this._utterance.volume = this._volume;
-                this._utterance.voice = this.voice;
-            }
-
-            speechSynthesis.cancel();
-            speechSynthesis.speak(this._utterance);
-        } catch (e) {
-            // NOP
-        }
-    }
-
-    pause() {
-        try {
-            speechSynthesis.cancel();
-        } catch (e) {
-            // NOP
-        }
-    }
-}
+/* global
+ * TextToSpeechAudio
+ */
 
 class AudioSystem {
     constructor({audioUriBuilder, requestBuilder=null, useCache}) {
diff --git a/ext/mixed/js/text-to-speech-audio.js b/ext/mixed/js/text-to-speech-audio.js
new file mode 100644
index 00000000..701933aa
--- /dev/null
+++ b/ext/mixed/js/text-to-speech-audio.js
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2020  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+class TextToSpeechAudio {
+    constructor(text, voice) {
+        this.text = text;
+        this.voice = voice;
+        this._utterance = null;
+        this._volume = 1;
+    }
+
+    get currentTime() {
+        return 0;
+    }
+    set currentTime(value) {
+        // NOP
+    }
+
+    get volume() {
+        return this._volume;
+    }
+    set volume(value) {
+        this._volume = value;
+        if (this._utterance !== null) {
+            this._utterance.volume = value;
+        }
+    }
+
+    async play() {
+        try {
+            if (this._utterance === null) {
+                this._utterance = new SpeechSynthesisUtterance(this.text || '');
+                this._utterance.lang = 'ja-JP';
+                this._utterance.volume = this._volume;
+                this._utterance.voice = this.voice;
+            }
+
+            speechSynthesis.cancel();
+            speechSynthesis.speak(this._utterance);
+        } catch (e) {
+            // NOP
+        }
+    }
+
+    pause() {
+        try {
+            speechSynthesis.cancel();
+        } catch (e) {
+            // NOP
+        }
+    }
+}