diff --git a/ext/bg/js/anki-note-builder.js b/ext/bg/js/anki-note-builder.js
index 0e17783b..1ccec20c 100644
--- a/ext/bg/js/anki-note-builder.js
+++ b/ext/bg/js/anki-note-builder.js
@@ -17,7 +17,8 @@
  */
 
 class AnkiNoteBuilder {
-    constructor({renderTemplate}) {
+    constructor({audioSystem, renderTemplate}) {
+        this._audioSystem = audioSystem;
         this._renderTemplate = renderTemplate;
     }
 
@@ -84,14 +85,14 @@ class AnkiNoteBuilder {
         });
     }
 
-    async injectAudio(definition, fields, sources, audioSystem, optionsContext) {
+    async injectAudio(definition, fields, sources, optionsContext) {
         if (!this._containsMarker(fields, 'audio')) { return; }
 
         try {
             const expressions = definition.expressions;
             const audioSourceDefinition = Array.isArray(expressions) ? expressions[0] : definition;
 
-            const {uri} = await audioSystem.getDefinitionAudio(audioSourceDefinition, sources, {tts: false, optionsContext});
+            const {uri} = await this.audioSystem.getDefinitionAudio(audioSourceDefinition, sources, {tts: false, optionsContext});
             const filename = this._createInjectedAudioFileName(audioSourceDefinition);
             if (filename !== null) {
                 definition.audio = {url: uri, filename};
diff --git a/ext/bg/js/backend.js b/ext/bg/js/backend.js
index 9e02cced..1fa7ede1 100644
--- a/ext/bg/js/backend.js
+++ b/ext/bg/js/backend.js
@@ -51,12 +51,16 @@ class Backend {
         this.anki = new AnkiNull();
         this.mecab = new Mecab();
         this.clipboardMonitor = new ClipboardMonitor({getClipboard: this._onApiClipboardGet.bind(this)});
-        this.ankiNoteBuilder = new AnkiNoteBuilder({renderTemplate: this._renderTemplate.bind(this)});
         this.options = null;
         this.optionsSchema = null;
         this.defaultAnkiFieldTemplates = null;
         this.audioSystem = new AudioSystem({getAudioUri: this._getAudioUri.bind(this)});
         this.audioUriBuilder = new AudioUriBuilder();
+        this.ankiNoteBuilder = new AnkiNoteBuilder({
+            audioSystem: this.audioSystem,
+            renderTemplate: this._renderTemplate.bind(this)
+        });
+
         this.optionsContext = {
             depth: 0,
             url: window.location.href
@@ -464,7 +468,6 @@ class Backend {
                 definition,
                 options.anki.terms.fields,
                 options.audio.sources,
-                this.audioSystem,
                 optionsContext
             );
         }