diff --git a/CHANGES.md b/CHANGES.md
index 1ea1dcb59..6a934dd98 100755
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,7 @@
 
 ### Bugfixes
 - Various IE11 fixes.
+- #907 Unnecessary login validation error when `default_domain` or `locked_domain` are set.
 - #908 Login form for inVerse is only 200px when `allow_registration` is set to `false`.
 - #909 Translations written as template literals [aren't parsed properly by xgettext](https://savannah.gnu.org/bugs/?50920).
 - #911 Use `getDefaultNickName` consistently to allow better overrides via plugins.
diff --git a/src/converse-controlbox.js b/src/converse-controlbox.js
index 8a46f62ec..b1f7821cf 100644
--- a/src/converse-controlbox.js
+++ b/src/converse-controlbox.js
@@ -405,6 +405,8 @@
                 },
 
                 authenticate (ev) {
+                    /* Authenticate the user based on a form submission event.
+                     */
                     if (ev && ev.preventDefault) { ev.preventDefault(); }
                     const $form = $(ev.target);
                     if (_converse.authentication === _converse.ANONYMOUS) {
@@ -418,10 +420,14 @@
                     let jid = $jid_input.val(),
                         errors = false;
 
-                    if (!jid || _.filter(jid.split('@')).length < 2) {
+                    if (!jid || (
+                            !_converse.locked_domain &&
+                            !_converse.default_domain &&
+                            _.filter(jid.split('@')).length < 2)) {
                         errors = true;
                         $jid_input.addClass('error');
                     }
+
                     if (!password && _converse.authentication !== _converse.EXTERNAL)  {
                         errors = true;
                         $pw_input.addClass('error');