--- a/toolkit/components/passwordmgr/test/unit/test_disabled_hosts.js
+++ b/toolkit/components/passwordmgr/test/unit/test_disabled_hosts.js
@@ -138,20 +138,46 @@ add_task(function test_rememberSignons()
 
   // Clean up.
   Services.logins.setLoginSavingEnabled(hostname2, true);
   LoginTestUtils.assertDisabledHostsEqual(Services.logins.getAllDisabledHosts(),
                                           []);
 });
 
 /**
- * Tests storing disabled hosts containing non-ASCII characters.
+ * Tests storing disabled hosts with non-ASCII characters where IDN is supported.
  */
-add_task(function* test_storage_setLoginSavingEnabled_nonascii()
+add_task(function* test_storage_setLoginSavingEnabled_nonascii_IDN_is_supported()
 {
-  let hostname = "http://" + String.fromCharCode(355) + ".example.com";
+  let hostname = "http://大.net";
+  let encoding = "http://xn--pss.net";
+
   Services.logins.setLoginSavingEnabled(hostname, false);
 
   yield* LoginTestUtils.reloadData();
+
+  Assert.equal(Services.logins.getLoginSavingEnabled(hostname), false);
+  Assert.equal(Services.logins.getLoginSavingEnabled(encoding), false);
   LoginTestUtils.assertDisabledHostsEqual(Services.logins.getAllDisabledHosts(),
                                           [hostname]);
+
   LoginTestUtils.clearData();
 });
+
+/**
+ * Tests storing disabled hosts with non-ASCII characters where IDN is not supported.
+ */
+add_task(function* test_storage_setLoginSavingEnabled_nonascii_IDN_not_supported()
+{
+  let hostname = "http://√.com";
+  let encoding = "http://xn--19g.com";
+
+  Services.logins.setLoginSavingEnabled(hostname, false);
+
+  yield* LoginTestUtils.reloadData();
+
+  Assert.equal(Services.logins.getLoginSavingEnabled(hostname), false);
+  Assert.equal(Services.logins.getLoginSavingEnabled(encoding), false);
+  LoginTestUtils.assertDisabledHostsEqual(Services.logins.getAllDisabledHosts(),
+                                          [encoding]);
+
+  LoginTestUtils.clearData();
+});