diff --git a/ext/bg/background.html b/ext/bg/background.html
index f1006f8d..3446d9ce 100644
--- a/ext/bg/background.html
+++ b/ext/bg/background.html
@@ -24,6 +24,7 @@
 
         <script src="/bg/js/anki.js"></script>
         <script src="/bg/js/anki-note-builder.js"></script>
+        <script src="/bg/js/backend.js"></script>
         <script src="/bg/js/mecab.js"></script>
         <script src="/bg/js/audio-uri-builder.js"></script>
         <script src="/bg/js/backend-api-forwarder.js"></script>
@@ -45,6 +46,6 @@
         <script src="/bg/js/util.js"></script>
         <script src="/mixed/js/audio-system.js"></script>
 
-        <script src="/bg/js/backend.js"></script>
+        <script src="/bg/js/background-main.js"></script>
     </body>
 </html>
diff --git a/ext/bg/context.html b/ext/bg/context.html
index 0e50ed7c..394869b1 100644
--- a/ext/bg/context.html
+++ b/ext/bg/context.html
@@ -185,6 +185,6 @@
         <script src="/bg/js/options.js"></script>
         <script src="/bg/js/util.js"></script>
 
-        <script src="/bg/js/context.js"></script>
+        <script src="/bg/js/context-main.js"></script>
     </body>
 </html>
diff --git a/ext/bg/js/backend.js b/ext/bg/js/backend.js
index 6b696f2c..693a9ad6 100644
--- a/ext/bg/js/backend.js
+++ b/ext/bg/js/backend.js
@@ -1059,6 +1059,3 @@ class Backend {
         }
     }
 }
-
-window.yomichanBackend = new Backend();
-window.yomichanBackend.prepare();
diff --git a/ext/bg/js/background-main.js b/ext/bg/js/background-main.js
new file mode 100644
index 00000000..24117f4e
--- /dev/null
+++ b/ext/bg/js/background-main.js
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2020  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* global
+ * Backend
+ */
+
+(async () => {
+    window.yomichanBackend = new Backend();
+    await window.yomichanBackend.prepare();
+})();
diff --git a/ext/bg/js/context.js b/ext/bg/js/context-main.js
similarity index 96%
rename from ext/bg/js/context.js
rename to ext/bg/js/context-main.js
index e3d4ad4a..e2086a96 100644
--- a/ext/bg/js/context.js
+++ b/ext/bg/js/context-main.js
@@ -51,7 +51,7 @@ function setupButtonEvents(selector, command, url) {
     }
 }
 
-window.addEventListener('DOMContentLoaded', async () => {
+async function mainInner() {
     await yomichan.prepare();
 
     showExtensionInfo();
@@ -86,4 +86,8 @@ window.addEventListener('DOMContentLoaded', async () => {
             }
         }, 10);
     });
-});
+}
+
+(async () => {
+    window.addEventListener('DOMContentLoaded', mainInner, false);
+})();
diff --git a/ext/bg/js/search-frontend.js b/ext/bg/js/search-main.js
similarity index 93%
rename from ext/bg/js/search-frontend.js
rename to ext/bg/js/search-main.js
index e534e771..38b6d99a 100644
--- a/ext/bg/js/search-frontend.js
+++ b/ext/bg/js/search-main.js
@@ -16,6 +16,7 @@
  */
 
 /* global
+ * DisplaySearch
  * apiOptionsGet
  */
 
@@ -27,7 +28,7 @@ function injectSearchFrontend() {
         '/fg/js/popup.js',
         '/fg/js/popup-proxy-host.js',
         '/fg/js/frontend.js',
-        '/fg/js/frontend-initialize.js'
+        '/fg/js/content-script-main.js'
     ];
     for (const src of scriptSrcs) {
         const node = document.querySelector(`script[src='${src}']`);
@@ -51,9 +52,12 @@ function injectSearchFrontend() {
     }
 }
 
-async function main() {
+(async () => {
     await yomichan.prepare();
 
+    const displaySearch = new DisplaySearch();
+    await displaySearch.prepare();
+
     let optionsApplied = false;
 
     const applyOptions = async () => {
@@ -74,6 +78,4 @@ async function main() {
     yomichan.on('optionsUpdated', applyOptions);
 
     await applyOptions();
-}
-
-main();
+})();
diff --git a/ext/bg/js/search.js b/ext/bg/js/search.js
index 006536c0..684ea6d3 100644
--- a/ext/bg/js/search.js
+++ b/ext/bg/js/search.js
@@ -73,12 +73,6 @@ class DisplaySearch extends Display {
         ]);
     }
 
-    static create() {
-        const instance = new DisplaySearch();
-        instance.prepare();
-        return instance;
-    }
-
     async prepare() {
         try {
             await super.prepare();
@@ -377,5 +371,3 @@ class DisplaySearch extends Display {
         }
     }
 }
-
-DisplaySearch.instance = DisplaySearch.create();
diff --git a/ext/bg/js/settings/popup-preview-frame-main.js b/ext/bg/js/settings/popup-preview-frame-main.js
new file mode 100644
index 00000000..86c2814c
--- /dev/null
+++ b/ext/bg/js/settings/popup-preview-frame-main.js
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2019-2020  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* global
+ * SettingsPopupPreview
+ */
+
+(async () => {
+    const instance = new SettingsPopupPreview();
+    await instance.prepare();
+})();
diff --git a/ext/bg/js/settings/popup-preview-frame.js b/ext/bg/js/settings/popup-preview-frame.js
index fba114e2..420a7c5a 100644
--- a/ext/bg/js/settings/popup-preview-frame.js
+++ b/ext/bg/js/settings/popup-preview-frame.js
@@ -41,12 +41,6 @@ class SettingsPopupPreview {
         ]);
     }
 
-    static create() {
-        const instance = new SettingsPopupPreview();
-        instance.prepare();
-        return instance;
-    }
-
     async prepare() {
         // Setup events
         window.addEventListener('message', this.onMessage.bind(this), false);
@@ -178,8 +172,3 @@ class SettingsPopupPreview {
         this.setInfoVisible(!this.popupShown);
     }
 }
-
-SettingsPopupPreview.instance = SettingsPopupPreview.create();
-
-
-
diff --git a/ext/bg/search.html b/ext/bg/search.html
index fe88e264..9a824776 100644
--- a/ext/bg/search.html
+++ b/ext/bg/search.html
@@ -94,6 +94,7 @@
         <script src="/bg/js/search-query-parser.js"></script>
         <script src="/bg/js/clipboard-monitor.js"></script>
         <script src="/bg/js/search.js"></script>
-        <script src="/bg/js/search-frontend.js"></script>
+
+        <script src="/bg/js/search-main.js"></script>
     </body>
 </html>
diff --git a/ext/bg/settings-popup-preview.html b/ext/bg/settings-popup-preview.html
index f33ecedf..66475b7c 100644
--- a/ext/bg/settings-popup-preview.html
+++ b/ext/bg/settings-popup-preview.html
@@ -129,5 +129,7 @@
         <script src="/fg/js/popup-proxy-host.js"></script>
         <script src="/fg/js/frontend.js"></script>
         <script src="/bg/js/settings/popup-preview-frame.js"></script>
+
+        <script src="/bg/js/settings/popup-preview-frame-main.js"></script>
     </body>
 </html>
diff --git a/ext/fg/float.html b/ext/fg/float.html
index c8ea9b67..07c3c9e6 100644
--- a/ext/fg/float.html
+++ b/ext/fg/float.html
@@ -57,6 +57,6 @@
 
         <script src="/fg/js/float.js"></script>
 
-        <script src="/fg/js/popup-nested.js"></script>
+        <script src="/fg/js/float-main.js"></script>
     </body>
 </html>
diff --git a/ext/fg/js/frontend-initialize.js b/ext/fg/js/content-script-main.js
similarity index 99%
rename from ext/fg/js/frontend-initialize.js
rename to ext/fg/js/content-script-main.js
index 2df59e20..14285536 100644
--- a/ext/fg/js/frontend-initialize.js
+++ b/ext/fg/js/content-script-main.js
@@ -61,7 +61,7 @@ async function createPopupProxy(depth, id, parentFrameId, url) {
     return popup;
 }
 
-async function main() {
+(async () => {
     await yomichan.prepare();
 
     const data = window.frontendInitializationData || {};
@@ -128,6 +128,4 @@ async function main() {
     window.addEventListener('fullscreenchange', applyOptions, false);
 
     await applyOptions();
-}
-
-main();
+})();
diff --git a/ext/fg/js/popup-nested.js b/ext/fg/js/float-main.js
similarity index 93%
rename from ext/fg/js/popup-nested.js
rename to ext/fg/js/float-main.js
index c140f9c8..f056f707 100644
--- a/ext/fg/js/popup-nested.js
+++ b/ext/fg/js/float-main.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019-2020  Yomichan Authors
+ * Copyright (C) 2020  Yomichan Authors
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -16,6 +16,7 @@
  */
 
 /* global
+ * DisplayFloat
  * apiOptionsGet
  */
 
@@ -26,7 +27,7 @@ function injectPopupNested() {
         '/fg/js/popup.js',
         '/fg/js/popup-proxy.js',
         '/fg/js/frontend.js',
-        '/fg/js/frontend-initialize.js'
+        '/fg/js/content-script-main.js'
     ];
     for (const src of scriptSrcs) {
         const script = document.createElement('script');
@@ -65,3 +66,7 @@ async function popupNestedInitialize(id, depth, parentFrameId, url) {
 
     await applyOptions();
 }
+
+(async () => {
+    new DisplayFloat();
+})();
diff --git a/ext/fg/js/float.js b/ext/fg/js/float.js
index 5c2c50c2..18d15a72 100644
--- a/ext/fg/js/float.js
+++ b/ext/fg/js/float.js
@@ -189,5 +189,3 @@ class DisplayFloat extends Display {
         }
     }
 }
-
-DisplayFloat.instance = new DisplayFloat();
diff --git a/ext/manifest.json b/ext/manifest.json
index d383dab0..4f35b03c 100644
--- a/ext/manifest.json
+++ b/ext/manifest.json
@@ -31,7 +31,7 @@
             "fg/js/popup-proxy.js",
             "fg/js/popup-proxy-host.js",
             "fg/js/frontend.js",
-            "fg/js/frontend-initialize.js"
+            "fg/js/content-script-main.js"
         ],
         "match_about_blank": true,
         "all_frames": true