diff --git a/ext/fg/js/float.js b/ext/fg/js/float.js
index 2debdeff..61d42fb3 100644
--- a/ext/fg/js/float.js
+++ b/ext/fg/js/float.js
@@ -32,12 +32,12 @@ class DisplayFloat extends Display {
         this._ownerFrameId = null;
         this._frameEndpoint = new FrameEndpoint();
         this._windowMessageHandlers = new Map([
-            ['configure',          {handler: this._onMessageConfigure.bind(this)}],
-            ['setOptionsContext',  {handler: this._onMessageSetOptionsContext.bind(this)}],
-            ['setContent',         {handler: this._onMessageSetContent.bind(this)}],
-            ['clearAutoPlayTimer', {handler: this._onMessageClearAutoPlayTimer.bind(this)}],
-            ['setCustomCss',       {handler: this._onMessageSetCustomCss.bind(this)}],
-            ['setContentScale',    {handler: this._onMessageSetContentScale.bind(this)}]
+            ['configure',          {async: true,  handler: this._onMessageConfigure.bind(this)}],
+            ['setOptionsContext',  {async: false, handler: this._onMessageSetOptionsContext.bind(this)}],
+            ['setContent',         {async: false, handler: this._onMessageSetContent.bind(this)}],
+            ['clearAutoPlayTimer', {async: false, handler: this._onMessageClearAutoPlayTimer.bind(this)}],
+            ['setCustomCss',       {async: false, handler: this._onMessageSetCustomCss.bind(this)}],
+            ['setContentScale',    {async: false, handler: this._onMessageSetContentScale.bind(this)}]
         ]);
 
         this.registerActions([
@@ -51,7 +51,9 @@ class DisplayFloat extends Display {
     async prepare() {
         await super.prepare();
 
-        window.addEventListener('message', this._onMessage.bind(this), false);
+        api.crossFrame.registerHandlers([
+            ['popupMessage', {async: 'dynamic', handler: this._onMessage.bind(this)}]
+        ]);
 
         this._frameEndpoint.signal();
     }
@@ -99,33 +101,23 @@ class DisplayFloat extends Display {
 
     // Message handling
 
-    _onMessage(e) {
-        let data = e.data;
-        if (!this._frameEndpoint.authenticate(data)) { return; }
-        data = data.data;
-
-        if (typeof data !== 'object' || data === null) {
-            this._logMessageError(e, 'Invalid data');
-            return;
-        }
-
-        const action = data.action;
-        if (typeof action !== 'string') {
-            this._logMessageError(e, 'Invalid data');
-            return;
+    _onMessage(data) {
+        if (!this._frameEndpoint.authenticate(data)) {
+            throw new Error('Invalid authentication');
         }
 
+        const {action, params} = data.data;
         const handlerInfo = this._windowMessageHandlers.get(action);
         if (typeof handlerInfo === 'undefined') {
-            this._logMessageError(e, `Invalid action: ${JSON.stringify(action)}`);
-            return;
+            throw new Error(`Invalid action: ${action}`);
         }
 
-        const handler = handlerInfo.handler;
-        handler(data.params);
+        const {async, handler} = handlerInfo;
+        const result = handler(params);
+        return {async, result};
     }
 
-    async _onMessageConfigure({messageId, frameId, ownerFrameId, popupId, optionsContext, childrenSupported, scale}) {
+    async _onMessageConfigure({frameId, ownerFrameId, popupId, optionsContext, childrenSupported, scale}) {
         this._ownerFrameId = ownerFrameId;
         this.setOptionsContext(optionsContext);
 
@@ -138,8 +130,6 @@ class DisplayFloat extends Display {
         }
 
         this._setContentScale(scale);
-
-        api.sendMessageToFrame(frameId, 'popupConfigured', {messageId});
     }
 
     _onMessageSetOptionsContext({optionsContext}) {
@@ -183,10 +173,6 @@ class DisplayFloat extends Display {
         body.style.fontSize = `${scale}em`;
     }
 
-    _logMessageError(event, type) {
-        yomichan.logWarning(new Error(`Popup received invalid message from origin ${JSON.stringify(event.origin)}: ${type}`));
-    }
-
     async _prepareNestedPopups(id, depth, parentFrameId, url) {
         let complete = false;
 
diff --git a/ext/fg/js/popup.js b/ext/fg/js/popup.js
index 78561de3..4f2de4f2 100644
--- a/ext/fg/js/popup.js
+++ b/ext/fg/js/popup.js
@@ -257,22 +257,7 @@ class Popup {
         await frameClient.connect(this._frame, this._targetOrigin, this._frameId, setupFrame);
 
         // Configure
-        const messageId = yomichan.generateId(16);
-        const popupPreparedPromise = yomichan.getTemporaryListenerResult(
-            chrome.runtime.onMessage,
-            (message, {resolve}) => {
-                if (
-                    isObject(message) &&
-                    message.action === 'popupConfigured' &&
-                    isObject(message.params) &&
-                    message.params.messageId === messageId
-                ) {
-                    resolve();
-                }
-            }
-        );
-        this._invokeApi('configure', {
-            messageId,
+        await this._invokeApi('configure', {
             frameId: this._frameId,
             ownerFrameId: this._ownerFrameId,
             popupId: this._id,
@@ -280,8 +265,6 @@ class Popup {
             childrenSupported: this._childrenSupported,
             scale: this._contentScale
         });
-
-        return popupPreparedPromise;
     }
 
     _onFrameLoad() {
@@ -456,12 +439,12 @@ class Popup {
         return dark ? 'dark' : 'light';
     }
 
-    _invokeApi(action, params={}) {
+    async _invokeApi(action, params={}) {
         const contentWindow = this._frame.contentWindow;
         if (this._frameClient === null || !this._frameClient.isConnected() || contentWindow === null) { return; }
 
         const message = this._frameClient.createMessage({action, params});
-        contentWindow.postMessage(message, this._targetOrigin);
+        return await api.crossFrame.invoke(this._frameClient.frameId, 'popupMessage', message);
     }
 
     _getFrameParentElement() {
diff --git a/ext/mixed/js/comm.js b/ext/mixed/js/comm.js
index 0d6b8695..182400e3 100644
--- a/ext/mixed/js/comm.js
+++ b/ext/mixed/js/comm.js
@@ -172,29 +172,22 @@ class CrossFrameAPIPort extends EventDispatcher {
             return;
         }
 
-        const {handler, async} = messageHandler;
+        let {handler, async} = messageHandler;
 
         this._sendAck(id);
-        if (async) {
-            this._invokeHandlerAsync(id, handler, params);
-        } else {
-            this._invokeHandler(id, handler, params);
-        }
-    }
-
-    _invokeHandler(id, handler, params) {
         try {
-            const result = handler(params);
-            this._sendResult(id, result);
-        } catch (error) {
-            this._sendError(id, error);
-        }
-    }
-
-    async _invokeHandlerAsync(id, handler, params) {
-        try {
-            const result = await handler(params);
-            this._sendResult(id, result);
+            let result = handler(params);
+            if (async === 'dynamic') {
+                ({async, result} = result);
+            }
+            if (async) {
+                result.then(
+                    (result2) => this._sendResult(id, result2),
+                    (error2) => this._sendError(id, error2)
+                );
+            } else {
+                this._sendResult(id, result);
+            }
         } catch (error) {
             this._sendError(id, error);
         }