diff --git a/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php b/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php
index 2b392563fe23..4ef0f5314062 100644
--- a/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php
+++ b/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php
@@ -2125,9 +2125,9 @@ protected function transformModelValue($key, $value)
      */
     public function append($attributes)
     {
-        $this->appends = array_unique(
+        $this->appends = array_values(array_unique(
             array_merge($this->appends, is_string($attributes) ? func_get_args() : $attributes)
-        );
+        ));
 
         return $this;
     }