diff --git a/app/Actions/Fortify/CreateNewUser.php b/app/Actions/Fortify/CreateNewUser.php
index 114f6a521..a1a0a8722 100644
--- a/app/Actions/Fortify/CreateNewUser.php
+++ b/app/Actions/Fortify/CreateNewUser.php
@@ -22,7 +22,7 @@ public function create(array $input)
     {
         Validator::make($input, [
             'name' => ['required', 'string', 'max:255'],
-            'username' => ['required', 'string', 'max:255', 'different:email', 'unique:users'],
+            'username' => ['required', 'string', 'max:255', 'alpha_dash:ascii', 'alpha_num:ascii', 'different:email', 'unique:users'],
             'email' => ['required', 'string', 'email', 'max:255', 'unique:users'],
             'password' => $this->passwordRules(),
             'terms' => Jetstream::hasTermsAndPrivacyPolicyFeature() ? ['required', 'accepted'] : '',
diff --git a/app/Actions/Fortify/UpdateUserProfileInformation.php b/app/Actions/Fortify/UpdateUserProfileInformation.php
index f888ecb8a..e7e9cc9ee 100644
--- a/app/Actions/Fortify/UpdateUserProfileInformation.php
+++ b/app/Actions/Fortify/UpdateUserProfileInformation.php
@@ -22,7 +22,7 @@ public function update($user, array $input)
     {
         Validator::make($input, [
             'name' => ['required', 'string', 'max:255'],
-            'username' => ['required', 'string', 'max:255', Rule::unique('users')->ignore($user->id)],
+            'username' => ['required', 'string', 'max:255', 'alpha_dash:ascii', 'alpha_num:ascii', 'different:email', Rule::unique('users')->ignore($user->id)],
             'email' => ['required', 'email', 'max:255', Rule::unique('users')->ignore($user->id)],
             'gender' => ['required', 'numeric'],
             'location' => ['nullable', 'max:255'],