diff --git a/browser/base/content/test/webextensions/head.js b/browser/base/content/test/webextensions/head.js
index c95243129eef..38a33f9c33a5 100644
--- a/browser/base/content/test/webextensions/head.js
+++ b/browser/base/content/test/webextensions/head.js
@@ -186,13 +186,7 @@ function triggerPageOptionsAction(win, action) {
 }
 
 function isDefaultIcon(icon) {
-  // These are basically the same icon, but code within webextensions
-  // generates references to the former and generic add-ons manager code
-  // generates referces to the latter.
-  return (
-    icon == "chrome://browser/content/extension.svg" ||
-    icon == "chrome://mozapps/skin/extensions/extensionGeneric.svg"
-  );
+  return icon == "chrome://mozapps/skin/extensions/extensionGeneric.svg";
 }
 
 /**
diff --git a/browser/components/extensions/extension.svg b/browser/components/extensions/extension.svg
deleted file mode 100644
index f8379128120b..000000000000
--- a/browser/components/extensions/extension.svg
+++ /dev/null
@@ -1,6 +0,0 @@
-<!-- This Source Code Form is subject to the terms of the Mozilla Public
-   - License, v. 2.0. If a copy of the MPL was not distributed with this
-   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16" width="16" height="16" fill="context-fill" fill-opacity="context-fill-opacity">
-  <path d="M2.6 8 4 8c1.103 0 2 .897 2 2s-.897 2-2 2l-1.4 0-.6.6 0 1.775C2 15.271 2.729 16 3.625 16l9.75 0c.896 0 1.625-.729 1.625-1.625l0-8.75C15 4.729 14.271 4 13.375 4L11 4l0-2c0-1.103-.897-2-2-2S7 .897 7 2l0 2-3.375 0C2.729 4 2 4.729 2 5.625L2 7.4l.6.6z"/>
-</svg>
diff --git a/browser/components/extensions/jar.mn b/browser/components/extensions/jar.mn
index ec42d5448fae..12136c4d31cb 100644
--- a/browser/components/extensions/jar.mn
+++ b/browser/components/extensions/jar.mn
@@ -14,7 +14,6 @@ browser.jar:
 #ifdef XP_WIN
     content/browser/extension-win-panel.css
 #endif
-    content/browser/extension.svg
     content/browser/ext-browser.json
     content/browser/parent/ext-bookmarks.js (parent/ext-bookmarks.js)
     content/browser/parent/ext-browser.js (parent/ext-browser.js)
diff --git a/browser/components/extensions/test/browser/browser_ext_browserAction_context.js b/browser/components/extensions/test/browser/browser_ext_browserAction_context.js
index c85249ce26fe..c6542dd01abf 100644
--- a/browser/components/extensions/test/browser/browser_ext_browserAction_context.js
+++ b/browser/components/extensions/test/browser/browser_ext_browserAction_context.js
@@ -591,7 +591,7 @@ add_task(async function testPropertyRemoval() {
     },
 
     getTests: function(tabs, windows) {
-      let defaultIcon = "chrome://browser/content/extension.svg";
+      let defaultIcon = "chrome://mozapps/skin/extensions/extensionGeneric.svg";
       let details = [
         {
           icon: browser.runtime.getURL("default.png"),
diff --git a/browser/components/extensions/test/browser/browser_ext_browserAction_pageAction_icon.js b/browser/components/extensions/test/browser/browser_ext_browserAction_pageAction_icon.js
index 1051e5f3642e..5c4c5725382c 100644
--- a/browser/components/extensions/test/browser/browser_ext_browserAction_pageAction_icon.js
+++ b/browser/components/extensions/test/browser/browser_ext_browserAction_pageAction_icon.js
@@ -365,7 +365,7 @@ add_task(async function testDetailsObjects() {
   await promiseAnimationFrame();
 
   // The initial icon should be the default icon since no icon is in the manifest.
-  const DEFAULT_ICON = "chrome://browser/content/extension.svg";
+  const DEFAULT_ICON = "chrome://mozapps/skin/extensions/extensionGeneric.svg";
   let browserActionButton = browserActionWidget.forWindow(window).node;
   let pageActionImage = document.getElementById(pageActionId);
   is(
diff --git a/browser/components/extensions/test/browser/browser_ext_pageAction_context.js b/browser/components/extensions/test/browser/browser_ext_pageAction_context.js
index 558b6de81eed..660ca7131cb0 100644
--- a/browser/components/extensions/test/browser/browser_ext_pageAction_context.js
+++ b/browser/components/extensions/test/browser/browser_ext_pageAction_context.js
@@ -51,7 +51,7 @@ add_task(async function testTabSwitchContext() {
     },
 
     getTests: function(tabs) {
-      let defaultIcon = "chrome://browser/content/extension.svg";
+      let defaultIcon = "chrome://mozapps/skin/extensions/extensionGeneric.svg";
       let details = [
         {
           icon: browser.runtime.getURL("default.png"),
diff --git a/browser/components/extensions/test/browser/browser_ext_sidebarAction_context.js b/browser/components/extensions/test/browser/browser_ext_sidebarAction_context.js
index 37b673783a5d..aade93a3c727 100644
--- a/browser/components/extensions/test/browser/browser_ext_sidebarAction_context.js
+++ b/browser/components/extensions/test/browser/browser_ext_sidebarAction_context.js
@@ -431,7 +431,7 @@ add_task(async function testPropertyRemoval() {
     },
 
     getTests: function(tabs, windows) {
-      let defaultIcon = "chrome://browser/content/extension.svg";
+      let defaultIcon = "chrome://mozapps/skin/extensions/extensionGeneric.svg";
       let details = [
         {
           icon: browser.runtime.getURL("default.png"),
diff --git a/browser/installer/allowed-dupes.mn b/browser/installer/allowed-dupes.mn
index b78182e949e6..2e9dd92cf49a 100644
--- a/browser/installer/allowed-dupes.mn
+++ b/browser/installer/allowed-dupes.mn
@@ -107,10 +107,7 @@ browser/chrome/browser/search-extensions/yandex/yandex-en.ico
 browser/chrome/browser/content/activity-stream/data/content/tippytop/favicons/yandex-ru.png
 browser/chrome/browser/search-extensions/yandex/yandex-ru.ico
 
-# Bug 1708008 - De-duplicate extension icons
-browser/chrome/browser/content/browser/extension.svg
-chrome/toolkit/skin/classic/mozapps/extensions/extension.svg
-chrome/toolkit/skin/classic/mozapps/extensions/extensionGeneric.svg
+# Bug 1720584 - De-duplicate theme and customize icons
 chrome/toolkit/skin/classic/mozapps/extensions/themeGeneric.svg
 browser/chrome/browser/skin/classic/browser/customize.svg
 
diff --git a/browser/themes/shared/notification-icons.inc.css b/browser/themes/shared/notification-icons.inc.css
index 658fa7f7430a..37f7d030b3d6 100644
--- a/browser/themes/shared/notification-icons.inc.css
+++ b/browser/themes/shared/notification-icons.inc.css
@@ -324,7 +324,7 @@
 }
 
 .popup-notification-icon[popupid="addon-install-confirmation"] {
-  list-style-image: url(chrome://browser/content/extension.svg);
+  list-style-image: url(chrome://mozapps/skin/extensions/extension.svg);
 }
 
 #addon-install-confirmation-notification[warning] .popup-notification-icon[popupid="addon-install-confirmation"] {
diff --git a/toolkit/components/extensions/ExtensionParent.jsm b/toolkit/components/extensions/ExtensionParent.jsm
index 39ce6d608b86..271941f252b2 100644
--- a/toolkit/components/extensions/ExtensionParent.jsm
+++ b/toolkit/components/extensions/ExtensionParent.jsm
@@ -1542,7 +1542,7 @@ function watchExtensionProxyContextLoad(
 // Manages icon details for toolbar buttons in the |pageAction| and
 // |browserAction| APIs.
 let IconDetails = {
-  DEFAULT_ICON: "chrome://browser/content/extension.svg",
+  DEFAULT_ICON: "chrome://mozapps/skin/extensions/extensionGeneric.svg",
 
   // WeakMap<Extension -> Map<url-string -> Map<iconType-string -> object>>>
   iconCache: new DefaultWeakMap(() => {
@@ -1662,7 +1662,7 @@ let IconDetails = {
   // Returns the appropriate icon URL for the given icons object and the
   // screen resolution of the given window.
   getPreferredIcon(icons, extension = null, size = 16) {
-    const DEFAULT = "chrome://browser/content/extension.svg";
+    const DEFAULT = "chrome://mozapps/skin/extensions/extensionGeneric.svg";
 
     let bestSize = null;
     if (icons[size]) {