diff --git a/toolkit/components/extensions/schemas/theme.json b/toolkit/components/extensions/schemas/theme.json
index a2811ae06820..174381613987 100644
--- a/toolkit/components/extensions/schemas/theme.json
+++ b/toolkit/components/extensions/schemas/theme.json
@@ -563,10 +563,6 @@
           "theme": {
             "$ref": "ThemeType"
           },
-          "default_locale": {
-            "type": "string",
-            "optional": "true"
-          },
           "icons": {
             "type": "object",
             "optional": true,
@@ -643,7 +639,7 @@
           },
           {
             "name": "details",
-            "$ref": "ThemeType",
+            "$ref": "manifest.ThemeType",
             "description": "The properties of the theme to update."
           }
         ]
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_webextension_theme.js b/toolkit/mozapps/extensions/test/xpcshell/test_webextension_theme.js
index 790b5b7e78ea..fc3cff9bd83d 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_webextension_theme.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_webextension_theme.js
@@ -224,34 +224,3 @@ add_task(async function uninstall_offers_undo() {
   theme.uninstall();
   await promiseRestartManager();
 });
-
-// Test that default_locale works with WE themes
-add_task(async function default_locale_themes() {
-  let addon = await promiseInstallWebExtension({
-    manifest: {
-      default_locale: "en",
-      name: "__MSG_name__",
-      description: "__MSG_description__",
-      theme: {
-        "accentcolor": "black",
-        "textcolor": "white",
-      }
-    },
-    files: {
-      "_locales/en/messages.json": `{
-        "name": {
-          "message": "the name"
-        },
-        "description": {
-          "message": "the description"
-        }
-      }`
-    }
-  });
-
-  addon = await promiseAddonByID(addon.id);
-  equal(addon.name, "the name");
-  equal(addon.description, "the description");
-  equal(addon.type, "theme");
-  addon.uninstall();
-});