diff --git a/CHANGELOG.md b/CHANGELOG.md
index 392b4fb..68ba4b4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,17 @@
 
 All notable changes to this project will be documented in this file. See [standard-version](https://github.com/conventional-changelog/standard-version) for commit guidelines.
 
+## [1.0.0](https://github.com/ParkerM/close-tabs-to-left/compare/v0.1.1...v1.0.0) (2021-05-21)
+
+
+### ⚠ BREAKING CHANGES
+
+* restrict max firefox version to avoid functional overlap
+
+### Features
+
+* restrict max firefox version to avoid functional overlap ([1465a5f](https://github.com/ParkerM/close-tabs-to-left/commit/1465a5f10e38472e5da9e054f12e34d5ea6cb0b8))
+
 ## [0.1.1](https://github.com/ParkerM/close-tabs-to-left/compare/v0.0.4...v0.1.1) (2021-05-21)
 
 **Note:** Dependency upgrades and first "minor" release  
diff --git a/README.md b/README.md
index f3aecf8..910730c 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,10 @@
 
 Firefox extension that adds "Close Tabs to the Left" context menu entry.
 
+# ⚠ Notice:
+As a result of "Close Tabs to the Left" becoming standard functionality in Firefox version 88,
+this extension will be restricted to Firefox versions 87 and below.
+
 ## Building
 See [package.json](./package.json) for more info on the yarn scripts mentioned here.
 
diff --git a/manifest.json b/manifest.json
index e519685..50d6d71 100644
--- a/manifest.json
+++ b/manifest.json
@@ -3,7 +3,7 @@
   "default_locale": "en",
   "name": "__MSG_extensionName__",
   "description": "__MSG_extensionDescription__",
-  "version": "0.1.1",
+  "version": "1.0.0",
   "homepage_url": "https://github.com/ParkerM/close-tabs-to-left",
   "developer": {
     "name": "Parker Mauney",
@@ -12,7 +12,8 @@
   "browser_specific_settings": {
     "gecko": {
       "id": "closetabstotheleft@parkerm.github.io",
-      "strict_min_version": "58.0a1"
+      "strict_min_version": "58.0a1",
+      "strict_max_version": "87.*"
     }
   },
   "background": {
diff --git a/package.json b/package.json
index 3139617..5a3f445 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "close-tabs-to-left",
-  "version": "0.1.1",
+  "version": "1.0.0",
   "main": "index.js",
   "license": "MIT",
   "repository": "github:ParkerM/close-tabs-to-left",