diff --git a/webextension/js/background/backgroundLogic.js b/webextension/js/background/backgroundLogic.js
index c044eb5..f55c5c7 100644
--- a/webextension/js/background/backgroundLogic.js
+++ b/webextension/js/background/backgroundLogic.js
@@ -63,8 +63,7 @@ const backgroundLogic = {
       url = undefined;
     }
 
-    // We can't open these we just have to throw them away
-    if (new URL(url).protocol === "about:") {
+    if (!this.isPermissibleURL(url)) {
       return;
     }
 
@@ -76,6 +75,17 @@ const backgroundLogic = {
     });
   },
 
+  isPermissibleURL(url) {
+    const protocol = new URL(url).protocol;
+    // We can't open these we just have to throw them away
+    if (protocol === "about:"
+        || protocol === "chrome:"
+        || protocol === "moz-extension:") {
+      return false;
+    }
+    return true;
+  },
+
   checkArgs(requiredArguments, options, methodName) {
     requiredArguments.forEach((argument) => {
       if (!(argument in options)) {
diff --git a/webextension/js/background/identityState.js b/webextension/js/background/identityState.js
index a563d90..fbb0020 100644
--- a/webextension/js/background/identityState.js
+++ b/webextension/js/background/identityState.js
@@ -41,6 +41,9 @@ const identityState = {
     const tabsByContainer = await browser.tabs.query({cookieStoreId, windowId});
     tabsByContainer.forEach((tab) => {
       const tabObject = this._createTabObject(tab);
+      if (!backgroundLogic.isPermissibleURL(tab.url)) {
+        return;
+      }
       // This tab is going to be closed. Let's mark this tabObject as
       // non-active.
       tabObject.active = false;