diff --git a/composer.json b/composer.json
index e8866dd..23c6e91 100644
--- a/composer.json
+++ b/composer.json
@@ -31,7 +31,7 @@
     "require": {
         "php": "^8.1",
         "yiisoft/rbac": "dev-master",
-        "yiisoft/var-dumper": "^1.0"
+        "yiisoft/var-dumper": "^1.7"
     },
     "require-dev": {
         "ext-uopz": "*",
diff --git a/src/AssignmentsStorage.php b/src/AssignmentsStorage.php
index ffed31e..0da3044 100644
--- a/src/AssignmentsStorage.php
+++ b/src/AssignmentsStorage.php
@@ -12,6 +12,8 @@
  *
  * It is suitable for authorization data that is not too big (for example, the authorization data for a personal blog
  * system).
+ *
+ * @psalm-import-type RawAssignment from SimpleAssignmentsStorage
  */
 final class AssignmentsStorage extends SimpleAssignmentsStorage
 {
@@ -86,25 +88,28 @@ public function clear(): void
 
     private function loadAssignments(): void
     {
-        /** @psalm-var array<string|int, string[]> $assignments */
+        /** @psalm-var list<RawAssignment> $assignments */
         $assignments = $this->loadFromFile($this->assignmentFile);
         $modifiedTime = @filemtime($this->assignmentFile);
-        foreach ($assignments as $userId => $roles) {
-            foreach ($roles as $role) {
-                /** @psalm-suppress InvalidPropertyAssignmentValue */
-                $this->assignments[$userId][$role] = new Assignment((string)$userId, $role, $modifiedTime);
-            }
+        foreach ($assignments as $assignment) {
+            /** @psalm-suppress InvalidPropertyAssignmentValue */
+            $this->assignments[$assignment['user_id']][$assignment['item_name']] = new Assignment(
+                userId: $assignment['user_id'],
+                itemName: $assignment['item_name'],
+                createdAt: $assignment['created_at'] ?? $modifiedTime
+            );
         }
     }
 
     private function saveAssignments(): void
     {
         $assignmentData = [];
-        foreach ($this->assignments as $userId => $assignments) {
-            foreach ($assignments as $assignment) {
-                $assignmentData[$userId][] = $assignment->getItemName();
+        foreach ($this->assignments as $userAssignments) {
+            foreach ($userAssignments as $userAssignment) {
+                $assignmentData[] = $userAssignment->getAttributes();
             }
         }
+
         $this->saveToFile($assignmentData, $this->assignmentFile);
     }
 }
diff --git a/src/ItemsStorage.php b/src/ItemsStorage.php
index e4b1822..e5efa24 100644
--- a/src/ItemsStorage.php
+++ b/src/ItemsStorage.php
@@ -94,13 +94,16 @@ private function save(): void
     {
         $items = [];
         foreach ($this->getAll() as $name => $item) {
-            $items[$name] = array_filter($item->getAttributes());
+            $data = array_filter($item->getAttributes());
             if ($this->hasChildren($name)) {
                 foreach ($this->getDirectChildren($name) as $child) {
-                    $items[$name]['children'][] = $child->getName();
+                    $data['children'][] = $child->getName();
                 }
             }
+
+            $items[] = $data;
         }
+
         $this->saveToFile($items, $this->itemFile);
     }
 
@@ -116,19 +119,17 @@ private function loadItems(): void
         /** @psalm-var array<string, RawItem> $items */
         $items = $this->loadFromFile($this->itemFile);
         $itemsMtime = @filemtime($this->itemFile);
-        foreach ($items as $name => $item) {
-            $this->items[$name] = $this
+        foreach ($items as $item) {
+            $this->items[$item['name']] = $this
                 ->getInstanceFromAttributes($item)
-                ->withCreatedAt($itemsMtime)
-                ->withUpdatedAt($itemsMtime);
+                ->withCreatedAt($item['created_at'] ?? $itemsMtime)
+                ->withUpdatedAt($item['updated_at'] ?? $itemsMtime);
         }
 
-        foreach ($items as $name => $item) {
-            if (isset($item['children'])) {
-                foreach ($item['children'] as $childName) {
-                    if ($this->hasItem($childName)) {
-                        $this->children[$name][$childName] = $this->items[$childName];
-                    }
+        foreach ($items as $item) {
+            foreach ($item['children'] ?? [] as $childName) {
+                if ($this->hasItem($childName)) {
+                    $this->children[$item['name']][$childName] = $this->items[$childName];
                 }
             }
         }
@@ -161,7 +162,7 @@ private function getInstanceFromAttributes(array $attributes): Permission|Role
             $item = $item->withDescription($description);
         }
 
-        $ruleName = $attributes['ruleName'] ?? null;
+        $ruleName = $attributes['rule_name'] ?? null;
         if ($ruleName !== null) {
             $item = $item->withRuleName($ruleName);
         }
diff --git a/tests/AssignmentsStorageTest.php b/tests/AssignmentsStorageTest.php
index d79e93e..356710f 100644
--- a/tests/AssignmentsStorageTest.php
+++ b/tests/AssignmentsStorageTest.php
@@ -37,4 +37,9 @@ protected function createAssignmentsStorage(): AssignmentsStorageInterface
     {
         return new AssignmentsStorage($this->getDataPath());
     }
+
+    protected function getAssignmentsStorageForModificationAssertions(): AssignmentsStorageInterface
+    {
+        return $this->createAssignmentsStorage();
+    }
 }
diff --git a/tests/ItemsStorageTest.php b/tests/ItemsStorageTest.php
index bc90565..2e71cc2 100644
--- a/tests/ItemsStorageTest.php
+++ b/tests/ItemsStorageTest.php
@@ -66,6 +66,11 @@ protected function createItemsStorage(): ItemsStorageInterface
         return new ItemsStorage($this->getDataPath());
     }
 
+    protected function getItemsStorageForModificationAssertions(): ItemsStorageInterface
+    {
+        return $this->createItemsStorage();
+    }
+
     private function getTempDirectory(): string
     {
         return __DIR__ . '/temp';