--- a/browser/extensions/formautofill/test/mochitest/test_address_level_1_submission.html
+++ b/browser/extensions/formautofill/test/mochitest/test_address_level_1_submission.html
@@ -24,16 +24,21 @@ const TEST_ADDRESSES = [{
   organization: "Mozilla",
   "street-address": "123 Sesame Street",
   "address-level1": "AL",
   country: "DE",
   timesUsed: 1,
 }];
 
 add_task(async function test_DE_is_valid_testcase() {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["extensions.formautofill.supportedCountries", "US,CA,DE"],
+    ],
+  });
   let chromeScript = SpecialPowers.loadChromeScript(function test_country_data() {
     ChromeUtils.import("resource://formautofill/FormAutofillUtils.jsm");
     let data = AddressDataLoader.getData("DE");
     /* global addMessageListener */
     addMessageListener("CheckSubKeys", () => {
       return !data.defaultLocale.sub_keys;
     });
   });