diff --git a/ext/bg/js/backend.js b/ext/bg/js/backend.js
index e849bc69..81578462 100644
--- a/ext/bg/js/backend.js
+++ b/ext/bg/js/backend.js
@@ -48,7 +48,7 @@ class Backend {
         this.messageToken = yomichan.generateId(16);
 
         this._messageHandlers = new Map([
-            ['isBackendReady', this._onApiIsBackendReady.bind(this)],
+            ['yomichanOnline', this._onApiYomichanOnline.bind(this)],
             ['optionsSchemaGet', this._onApiOptionsSchemaGet.bind(this)],
             ['optionsGet', this._onApiOptionsGet.bind(this)],
             ['optionsGetFull', this._onApiOptionsGetFull.bind(this)],
@@ -114,17 +114,22 @@ class Backend {
         }
 
         this.clipboardMonitor.onClipboardText = this._onClipboardText.bind(this);
+
+        this._sendMessageAllTabs('backendPrepared');
+    }
+
+    _sendMessageAllTabs(action, params={}) {
+        const callback = () => this.checkLastError(chrome.runtime.lastError);
+        chrome.tabs.query({}, (tabs) => {
+            for (const tab of tabs) {
+                chrome.tabs.sendMessage(tab.id, {action, params}, callback);
+            }
+        });
     }
 
     onOptionsUpdated(source) {
         this.applyOptions();
-
-        const callback = () => this.checkLastError(chrome.runtime.lastError);
-        chrome.tabs.query({}, (tabs) => {
-            for (const tab of tabs) {
-                chrome.tabs.sendMessage(tab.id, {action: 'optionsUpdated', params: {source}}, callback);
-            }
-        });
+        this._sendMessageAllTabs('optionsUpdated', {source});
     }
 
     onMessage({action, params}, sender, callback) {
@@ -268,8 +273,11 @@ class Backend {
 
     // Message handlers
 
-    async _onApiIsBackendReady() {
-        return true;
+    async _onApiYomichanOnline(_params, sender) {
+        const tabId = sender.tab.id;
+        return new Promise((resolve) => {
+            chrome.tabs.sendMessage(tabId, {action: 'backendPrepared'}, resolve);
+        });
     }
 
     async _onApiOptionsSchemaGet() {
diff --git a/ext/bg/js/search-frontend.js b/ext/bg/js/search-frontend.js
index 509c4009..453a0b79 100644
--- a/ext/bg/js/search-frontend.js
+++ b/ext/bg/js/search-frontend.js
@@ -19,6 +19,8 @@
 /*global apiOptionsGet*/
 
 async function searchFrontendSetup() {
+    await yomichan.prepare();
+
     const optionsContext = {
         depth: 0,
         url: window.location.href
diff --git a/ext/bg/js/search.js b/ext/bg/js/search.js
index 0a7a5fe1..f3cba7ae 100644
--- a/ext/bg/js/search.js
+++ b/ext/bg/js/search.js
@@ -68,9 +68,8 @@ class DisplaySearch extends Display {
 
     async prepare() {
         try {
-            const superPromise = super.prepare();
-            const queryParserPromise = this.queryParser.prepare();
-            await Promise.all([superPromise, queryParserPromise]);
+            await super.prepare();
+            await this.queryParser.prepare();
 
             const {queryParams: {query='', mode=''}} = parseUrl(window.location.href);
 
diff --git a/ext/fg/js/frontend.js b/ext/fg/js/frontend.js
index 929ab56a..203366c3 100644
--- a/ext/fg/js/frontend.js
+++ b/ext/fg/js/frontend.js
@@ -52,6 +52,7 @@ class Frontend extends TextScanner {
 
     async prepare() {
         try {
+            await yomichan.prepare();
             await this.updateOptions();
             const {zoomFactor} = await apiGetZoom();
             this._pageZoomFactor = zoomFactor;
diff --git a/ext/mixed/js/api.js b/ext/mixed/js/api.js
index fa61a1e2..26f4389d 100644
--- a/ext/mixed/js/api.js
+++ b/ext/mixed/js/api.js
@@ -122,30 +122,6 @@ function apiGetDefaultAnkiFieldTemplates() {
 }
 
 function _apiInvoke(action, params={}) {
-    if (!_isBackendReady) {
-        if (_isBackendReadyPromise === null) {
-            _isBackendReadyPromise = new Promise((resolve) => (_isBackendReadyResolve = resolve));
-            const checkBackendReady = async () => {
-                try {
-                    if (await _apiInvokeRaw('isBackendReady')) {
-                        _isBackendReady = true;
-                        _isBackendReadyResolve();
-                    }
-                } catch (e) {
-                    // NOP
-                }
-                setTimeout(checkBackendReady, 100); // poll Backend until it responds
-            };
-            checkBackendReady();
-        }
-        return _isBackendReadyPromise.then(
-            () => _apiInvokeRaw(action, params)
-        );
-    }
-    return _apiInvokeRaw(action, params);
-}
-
-function _apiInvokeRaw(action, params={}) {
     const data = {action, params};
     return new Promise((resolve, reject) => {
         try {
@@ -172,7 +148,3 @@ function _apiInvokeRaw(action, params={}) {
 function _apiCheckLastError() {
     // NOP
 }
-
-let _isBackendReady = false;
-let _isBackendReadyResolve = null;
-let _isBackendReadyPromise = null;
diff --git a/ext/mixed/js/core.js b/ext/mixed/js/core.js
index 83813796..a3cb2459 100644
--- a/ext/mixed/js/core.js
+++ b/ext/mixed/js/core.js
@@ -269,17 +269,26 @@ const yomichan = (() => {
         constructor() {
             super();
 
+            this._isBackendPreparedResolve = null;
+            this._isBackendPreparedPromise = new Promise((resolve) => (this._isBackendPreparedResolve = resolve));
+
             this._messageHandlers = new Map([
+                ['backendPrepared', this._onBackendPrepared.bind(this)],
                 ['getUrl', this._onMessageGetUrl.bind(this)],
                 ['optionsUpdated', this._onMessageOptionsUpdated.bind(this)],
                 ['zoomChanged', this._onMessageZoomChanged.bind(this)]
             ]);
 
             chrome.runtime.onMessage.addListener(this._onMessage.bind(this));
+            chrome.runtime.sendMessage({action: 'yomichanOnline'});
         }
 
         // Public
 
+        prepare() {
+            return this._isBackendPreparedPromise;
+        }
+
         generateId(length) {
             const array = new Uint8Array(length);
             window.crypto.getRandomValues(array);
@@ -305,6 +314,10 @@ const yomichan = (() => {
             return false;
         }
 
+        _onBackendPrepared() {
+            this._isBackendPreparedResolve();
+        }
+
         _onMessageGetUrl() {
             return {url: window.location.href};
         }
diff --git a/ext/mixed/js/display.js b/ext/mixed/js/display.js
index e3e5e7df..6a762a65 100644
--- a/ext/mixed/js/display.js
+++ b/ext/mixed/js/display.js
@@ -153,6 +153,7 @@ class Display {
     }
 
     async prepare(options=null) {
+        await yomichan.prepare();
         const displayGeneratorPromise = this.displayGenerator.prepare();
         const updateOptionsPromise = this.updateOptions(options);
         await Promise.all([displayGeneratorPromise, updateOptionsPromise]);