diff --git a/ProjectLighthouse/Pages/RegisterForm.cshtml b/ProjectLighthouse/Pages/RegisterForm.cshtml
index 54775d85..93e9dfd5 100644
--- a/ProjectLighthouse/Pages/RegisterForm.cshtml
+++ b/ProjectLighthouse/Pages/RegisterForm.cshtml
@@ -38,7 +38,7 @@
     <div class="field">
         <label>Username</label>
         <div class="ui left icon input">
-            <input type="text" name="username" id="text" placeholder="Username">
+            <input type="text" name="username" id="text" placeholder="Username" pattern="^[a-zA-Z0-9_.-]*$" minlength="3" maxlength="16">
             <i class="user icon"></i>
         </div>
     </div>