diff --git a/common/Context.js b/common/Context.js
index 5de989b..6347f0a 100644
--- a/common/Context.js
+++ b/common/Context.js
@@ -230,7 +230,8 @@ export class Context {
             this.descendantTabs :
             [this.tab, ...this.descendantTabs];
 
-    if (this.withContainer) {
+    if (this.withContainer &&
+        browser.contextualIdentities) {
       const cookieStoreIds = [...new Set(this.$tabsToCopy.map(tab => tab.cookieStoreId))];
       this.$containerNameById = new Map();
       await Promise.all(
diff --git a/manifest.json b/manifest.json
index 18d4a37..03ec563 100644
--- a/manifest.json
+++ b/manifest.json
@@ -7,7 +7,6 @@
   "permissions": [
     "activeTab",
     "clipboardWrite",
-    "contextualIdentities",
     "cookies",
     "menus",
     "notifications",
@@ -15,6 +14,7 @@
     "tabs"
   ],
   "optional_permissions": [
+    "contextualIdentities",
     "<all_urls>"
   ],
   "icons": {