diff --git a/src/Illuminate/Database/Eloquent/Concerns/HasTimestamps.php b/src/Illuminate/Database/Eloquent/Concerns/HasTimestamps.php
index 8de099c998cd..b9c049b36482 100644
--- a/src/Illuminate/Database/Eloquent/Concerns/HasTimestamps.php
+++ b/src/Illuminate/Database/Eloquent/Concerns/HasTimestamps.php
@@ -110,7 +110,7 @@ public function usesTimestamps()
     /**
      * Get the name of the "created at" column.
      *
-     * @return string
+     * @return string|null
      */
     public function getCreatedAtColumn()
     {
@@ -120,7 +120,7 @@ public function getCreatedAtColumn()
     /**
      * Get the name of the "updated at" column.
      *
-     * @return string
+     * @return string|null
      */
     public function getUpdatedAtColumn()
     {
diff --git a/src/Illuminate/Database/Eloquent/Model.php b/src/Illuminate/Database/Eloquent/Model.php
index b4bb8eb3bff2..52d2dd40a998 100644
--- a/src/Illuminate/Database/Eloquent/Model.php
+++ b/src/Illuminate/Database/Eloquent/Model.php
@@ -144,14 +144,14 @@ abstract class Model implements Arrayable, ArrayAccess, Jsonable, JsonSerializab
     /**
      * The name of the "created at" column.
      *
-     * @var string
+     * @var string|null
      */
     const CREATED_AT = 'created_at';
 
     /**
      * The name of the "updated at" column.
      *
-     * @var string
+     * @var string|null
      */
     const UPDATED_AT = 'updated_at';