diff --git a/ext/bg/js/audio.js b/ext/bg/js/audio.js
index 3bcfc4e7..c94121ae 100644
--- a/ext/bg/js/audio.js
+++ b/ext/bg/js/audio.js
@@ -171,7 +171,7 @@ async function audioInject(definition, fields, sources, optionsContext, audioSys
         const expressions = definition.expressions;
         const audioSourceDefinition = Array.isArray(expressions) ? expressions[0] : definition;
 
-        const {uri} = await audioSystem.getExpressionAudio(audioSourceDefinition, sources, {tts: false, optionsContext});
+        const {uri} = await audioSystem.getDefinitionAudio(audioSourceDefinition, sources, {tts: false, optionsContext});
         const filename = audioBuildFilename(audioSourceDefinition);
         if (filename !== null) {
             definition.audio = {url: uri, filename};
diff --git a/ext/mixed/js/audio.js b/ext/mixed/js/audio.js
index 1da5d48c..31c476b1 100644
--- a/ext/mixed/js/audio.js
+++ b/ext/mixed/js/audio.js
@@ -78,16 +78,16 @@ class AudioSystem {
         }
     }
 
-    async getExpressionAudio(expression, sources, details) {
-        const key = `${expression.expression}:${expression.reading}`;
-        const cacheValue = this._cache.get(expression);
+    async getDefinitionAudio(definition, sources, details) {
+        const key = `${definition.expression}:${definition.reading}`;
+        const cacheValue = this._cache.get(definition);
         if (typeof cacheValue !== 'undefined') {
             const {audio, uri, source} = cacheValue;
             return {audio, uri, source};
         }
 
         for (const source of sources) {
-            const uri = await this._getAudioUri(expression, source, details);
+            const uri = await this._getAudioUri(definition, source, details);
             if (uri === null) { continue; }
 
             try {
diff --git a/ext/mixed/js/display.js b/ext/mixed/js/display.js
index 9d2746fd..3fe8e684 100644
--- a/ext/mixed/js/display.js
+++ b/ext/mixed/js/display.js
@@ -775,7 +775,7 @@ class Display {
             const sources = this.options.audio.sources;
             let audio, source, info;
             try {
-                ({audio, source} = await this.audioSystem.getExpressionAudio(expression, sources));
+                ({audio, source} = await this.audioSystem.getDefinitionAudio(expression, sources));
                 info = `From source ${1 + sources.indexOf(source)}: ${source}`;
             } catch (e) {
                 if (this.audioFallback === null) {