diff --git a/ext/mixed/js/core.js b/ext/mixed/js/core.js
index 7fb3c32e..5f9e172d 100644
--- a/ext/mixed/js/core.js
+++ b/ext/mixed/js/core.js
@@ -318,13 +318,6 @@ const yomichan = (() => {
         }
 
         getTemporaryListenerResult(eventHandler, userCallback, timeout=null) {
-            let resolve;
-            let reject;
-            const listenerPromise = new Promise((_resolve, _reject) => {
-                resolve = _resolve;
-                reject = _reject;
-            });
-
             if (
                 typeof eventHandler.addListener === 'undefined' ||
                 typeof eventHandler.removeListener === 'undefined'
@@ -332,32 +325,32 @@ const yomichan = (() => {
                 throw new Error('Event handler type not supported');
             }
 
-            const runtimeMessageCallback = ({action, params}, sender, sendResponse) => {
-                let timeoutId = null;
-                if (timeout !== null) {
-                    timeoutId = window.setTimeout(() => {
-                        timeoutId = null;
-                        eventHandler.removeListener(runtimeMessageCallback);
-                        reject(new Error(`Listener timed out in ${timeout} ms`));
-                    }, timeout);
-                }
-
-                const cleanupResolve = (value) => {
-                    if (timeoutId !== null) {
-                        window.clearTimeout(timeoutId);
-                        timeoutId = null;
+            return new Promise((resolve, reject) => {
+                const runtimeMessageCallback = ({action, params}, sender, sendResponse) => {
+                    let timeoutId = null;
+                    if (timeout !== null) {
+                        timeoutId = window.setTimeout(() => {
+                            timeoutId = null;
+                            eventHandler.removeListener(runtimeMessageCallback);
+                            reject(new Error(`Listener timed out in ${timeout} ms`));
+                        }, timeout);
                     }
-                    eventHandler.removeListener(runtimeMessageCallback);
-                    sendResponse();
-                    resolve(value);
+
+                    const cleanupResolve = (value) => {
+                        if (timeoutId !== null) {
+                            window.clearTimeout(timeoutId);
+                            timeoutId = null;
+                        }
+                        eventHandler.removeListener(runtimeMessageCallback);
+                        sendResponse();
+                        resolve(value);
+                    };
+
+                    userCallback({action, params}, {resolve: cleanupResolve, sender});
                 };
 
-                userCallback({action, params}, {resolve: cleanupResolve, sender});
-            };
-
-            eventHandler.addListener(runtimeMessageCallback);
-
-            return listenerPromise;
+                eventHandler.addListener(runtimeMessageCallback);
+            });
         }
 
         // Private