diff --git a/application/controllers/ApiV1ContactsController.php b/application/controllers/ApiV1ContactsController.php
index 90cc9d85a..7e08f1bd3 100644
--- a/application/controllers/ApiV1ContactsController.php
+++ b/application/controllers/ApiV1ContactsController.php
@@ -221,11 +221,16 @@ function (Filter\Condition $condition) {
 
                 $contactId = $this->getContactId($identifier);
                 if ($contactId !== null) {
-                    $db->update('contact', [
+                    $toUpdate = [
                         'full_name'             => $data['full_name'],
-                        'username'              => $data['username'] ?? null,
                         'default_channel_id'    => $this->getChannelId($data['default_channel'])
-                    ], ['id = ?' => $contactId]);
+                    ];
+
+                    if (! empty($data['username'])) {
+                        $toUpdate['username'] = $data['username'];
+                    }
+
+                    $db->update('contact', $toUpdate, ['id = ?' => $contactId]);
 
                     $db->delete('contact_address', ['contact_id = ?' => $contactId]);
                     $db->delete('contactgroup_member', ['contact_id = ?' => $contactId]);