diff --git a/app/models/Data/User.php b/app/models/Data/User.php
index 8c67250..335a874 100644
--- a/app/models/Data/User.php
+++ b/app/models/Data/User.php
@@ -48,19 +48,31 @@ class User extends Base
 
     public function validation()
     {
-        // Validation
-        $validator = new Validation();
+        $rules = [
+            'username' => new CallbackValidator([
+                'callback' => function () {
+                    return $this->findFirstByUsername($this->getUsername()) === false;
+                },
+                'message' => 'The username already exists.'
+            ]),
+            'email' => new CallbackValidator([
+                'callback' => function() {
+                    return $this->findFirstByEmail($this->getEmail()) === false;
+                },
+                'message' => 'The email address already exists.'
+            ])
+        ];
 
-        $validator->add('username', new CallbackValidator([
-            'callback' => function() { return $this->findFirstByUsername($this->getUsername()) === false; },
-            'message' => 'The username already exists.'
-        ]));
-        $validator->add('email', new CallbackValidator([
-            'callback' => function() { return $this->findFirstByEmail($this->getEmail()) === false; },
-            'message' => 'The email address already exists.'
-        ]));
+        $validation = new Validation();
+        foreach($rules as $field => $validator) {
 
-        return $this->validate($validator);
+            // Only validate changed fields.
+            if ($this->hasChanged($field)) {
+                $validation->add($field, $validator);
+            }
+        }
+
+        return $this->validate($validation);
     }
 
     /**