diff --git a/src/Item.php b/src/Item.php
index 88d87b62..82e034ab 100644
--- a/src/Item.php
+++ b/src/Item.php
@@ -10,8 +10,8 @@
  */
 abstract class Item
 {
-    public const TYPE_ROLE = 'role';
-    public const TYPE_PERMISSION = 'permission';
+    public const TYPE_ROLE = 1;
+    public const TYPE_PERMISSION = 2;
 
     /**
      * @var string The item description.
@@ -41,9 +41,10 @@ final public function __construct(private string $name)
     }
 
     /**
-     * @return string Type of the item.
+     * @return int Type of the item.
+     * @psalm-return Item::TYPE_*
      */
-    abstract public function getType(): string;
+    abstract public function getType(): int;
 
     /**
      * @return string Authorization item name.
@@ -139,7 +140,7 @@ final public function hasUpdatedAt(): bool
      *     name: string,
      *     description: string,
      *     rule_name: string|null,
-     *     type: string,
+     *     type: Item::TYPE_*,
      *     updated_at: int|null,
      *     created_at: int|null,
      * }
diff --git a/src/Permission.php b/src/Permission.php
index c3d7a493..fdde75b2 100644
--- a/src/Permission.php
+++ b/src/Permission.php
@@ -6,7 +6,7 @@
 
 final class Permission extends Item
 {
-    public function getType(): string
+    public function getType(): int
     {
         return self::TYPE_PERMISSION;
     }
diff --git a/src/Role.php b/src/Role.php
index 2aef818a..aef4c55a 100644
--- a/src/Role.php
+++ b/src/Role.php
@@ -6,7 +6,7 @@
 
 final class Role extends Item
 {
-    public function getType(): string
+    public function getType(): int
     {
         return self::TYPE_ROLE;
     }
diff --git a/src/SimpleItemsStorage.php b/src/SimpleItemsStorage.php
index 4646a796..7e6c946d 100644
--- a/src/SimpleItemsStorage.php
+++ b/src/SimpleItemsStorage.php
@@ -239,7 +239,7 @@ private function updateItemName(string $name, Item $item): void
      *
      * @psalm-return ($type is Item::TYPE_PERMISSION ? array<string, Permission> : array<string, Role>)
      */
-    private function getItemsByType(string $type): array
+    private function getItemsByType(int $type): array
     {
         return array_filter(
             $this->getAll(),
@@ -250,7 +250,7 @@ private function getItemsByType(string $type): array
     /**
      * @psalm-param Item::TYPE_* $type
      */
-    private function removeItemsByType(string $type): void
+    private function removeItemsByType(int $type): void
     {
         foreach ($this->getItemsByType($type) as $item) {
             $this->remove($item->getName());
diff --git a/tests/Common/ManagerLogicTestTrait.php b/tests/Common/ManagerLogicTestTrait.php
index 0cf012a6..e1c416c5 100644
--- a/tests/Common/ManagerLogicTestTrait.php
+++ b/tests/Common/ManagerLogicTestTrait.php
@@ -14,6 +14,7 @@
 use Yiisoft\Rbac\Exception\ItemAlreadyExistsException;
 use Yiisoft\Rbac\Exception\RuleInterfaceNotImplementedException;
 use Yiisoft\Rbac\Exception\RuleNotFoundException;
+use Yiisoft\Rbac\Item;
 use Yiisoft\Rbac\Permission;
 use Yiisoft\Rbac\Role;
 use Yiisoft\Rbac\RuleInterface;
@@ -727,7 +728,7 @@ public function testAddRole(): void
                 'name' => 'new role',
                 'description' => 'new role description',
                 'rule_name' => TrueRule::class,
-                'type' => 'role',
+                'type' => Item::TYPE_ROLE,
                 'updated_at' => 1_642_026_148,
                 'created_at' => 1_642_026_147,
             ],
@@ -792,7 +793,7 @@ public function testAddPermission(): void
                 'name' => 'edit post',
                 'description' => 'edit a post',
                 'rule_name' => null,
-                'type' => 'permission',
+                'type' => Item::TYPE_PERMISSION,
                 'updated_at' => 1_642_026_148,
                 'created_at' => 1_642_026_147,
             ],