diff --git a/include/constants.php b/include/constants.php
index be8e3f16..3f30d339 100644
--- a/include/constants.php
+++ b/include/constants.php
@@ -1,6 +1,6 @@
 <?php
 defined('VERSION_NUMBER') || define('VERSION_NUMBER', '1.8.7');
-defined('RELEASE_DATE') || define('RELEASE_DATE', '2023-08-28');
+defined('RELEASE_DATE') || define('RELEASE_DATE', '2023-08-29');
 defined('IN_TRACKER') || define('IN_TRACKER', false);
 defined('PROJECTNAME') || define("PROJECTNAME","NexusPHP");
 defined('NEXUSPHPURL') || define("NEXUSPHPURL","https://nexusphp.org");
diff --git a/public/takeinvite.php b/public/takeinvite.php
index aa32e912..f65a1e41 100644
--- a/public/takeinvite.php
+++ b/public/takeinvite.php
@@ -39,6 +39,9 @@ if ($isPreRegisterEmailAndUsername) {
     if (empty($preRegisterUsername)) {
         bark(nexus_trans("invite.require_pre_register_username"));
     }
+    if (!validusername($preRegisterUsername)) {
+        bark(nexus_trans("user.username_invalid", ["username" => $preRegisterUsername]));
+    }
     $exists = \App\Models\User::query()->where('username', $preRegisterUsername)->exists();
     if ($exists) {
         bark(nexus_trans("user.username_already_exists", ["username" => $preRegisterUsername]));
diff --git a/resources/lang/en/user.php b/resources/lang/en/user.php
index 53d09be8..58531519 100644
--- a/resources/lang/en/user.php
+++ b/resources/lang/en/user.php
@@ -55,4 +55,5 @@ return [
         ],
     ],
     'username_already_exists' => 'Username::username already exists',
+    'username_invalid' => 'Username::username invalid',
 ];
diff --git a/resources/lang/zh_CN/user.php b/resources/lang/zh_CN/user.php
index f797b8d2..733152dd 100644
--- a/resources/lang/zh_CN/user.php
+++ b/resources/lang/zh_CN/user.php
@@ -55,4 +55,5 @@ return [
         ],
     ],
     'username_already_exists' => '用户名：:username 已经存在',
+    'username_invalid' => '用户名：:username 无效',
 ];
diff --git a/resources/lang/zh_TW/user.php b/resources/lang/zh_TW/user.php
index cf97e58b..758cb269 100644
--- a/resources/lang/zh_TW/user.php
+++ b/resources/lang/zh_TW/user.php
@@ -55,4 +55,5 @@ return [
         ],
     ],
     'username_already_exists' => '用戶名：:username 已經存在',
+    'username_invalid' => '用戶名：:username 無效',
 ];