--- a/browser/components/extensions/ext-tabs.js
+++ b/browser/components/extensions/ext-tabs.js
@@ -440,17 +440,17 @@ this.tabs = class extends ExtensionAPI {
             if (updateProperties.active) {
               tabbrowser.selectedTab = nativeTab;
             } else {
               // Not sure what to do here? Which tab should we select?
             }
           }
           if (updateProperties.muted !== null) {
             if (nativeTab.muted != updateProperties.muted) {
-              nativeTab.toggleMuteAudio(extension.uuid);
+              nativeTab.toggleMuteAudio(extension.id);
             }
           }
           if (updateProperties.pinned !== null) {
             if (updateProperties.pinned) {
               tabbrowser.pinTab(nativeTab);
             } else {
               tabbrowser.unpinTab(nativeTab);
             }

--- a/browser/components/extensions/test/browser/browser_ext_tabs_audio.js
+++ b/browser/components/extensions/test/browser/browser_ext_tabs_audio.js
@@ -110,31 +110,29 @@ add_task(async function() {
       }
       for (let obj of [muted.changeInfo, muted.tab]) {
         browser.test.assertEq(true, obj.mutedInfo.muted, "Tab is muted");
       }
 
       for (let obj of [nonMuted.changeInfo, nonMuted.tab, muted.changeInfo, muted.tab]) {
         browser.test.assertEq("extension", obj.mutedInfo.reason, "Mute state changed by extension");
 
-        // FIXME: browser.runtime.id is currently broken.
-        browser.test.assertEq(browser.i18n.getMessage("@@extension_id"),
+        browser.test.assertEq(browser.runtime.id,
                               obj.mutedInfo.extensionId,
                               "Mute state changed by extension");
       }
 
       browser.test.log("Test that mutedInfo is preserved by sessionstore");
       let tab = await changeTab(tabIds[1], "duplicate").then(browser.tabs.get);
 
       browser.test.assertEq(true, tab.mutedInfo.muted, "Tab is muted");
 
       browser.test.assertEq("extension", tab.mutedInfo.reason, "Mute state changed by extension");
 
-      // FIXME: browser.runtime.id is currently broken.
-      browser.test.assertEq(browser.i18n.getMessage("@@extension_id"),
+      browser.test.assertEq(browser.runtime.id,
                             tab.mutedInfo.extensionId,
                             "Mute state changed by extension");
 
       browser.test.log("Unmute externally, and check results");
       [nonMuted] = await Promise.all([
         promiseUpdated(tabIds[1], "mutedInfo"),
         changeTab(tabIds[1], "muted", false),
         browser.tabs.remove(tab.id),