diff --git a/djangochannelsrestframework/observer/model_observer.py b/djangochannelsrestframework/observer/model_observer.py
index d9bd7c5..56b3f32 100644
--- a/djangochannelsrestframework/observer/model_observer.py
+++ b/djangochannelsrestframework/observer/model_observer.py
@@ -4,7 +4,7 @@
 from enum import Enum
 from functools import partial
 from typing import Type, Dict, Any, Set, Optional
-from uuid import uuid4
+from uuid import uuid4, UUID
 
 from asgiref.sync import async_to_sync
 from channels.layers import get_channel_layer
@@ -182,6 +182,10 @@ def serialize(self, instance, action, **kwargs) -> Dict[str, Any]:
         else:
             message_body["pk"] = instance.pk
 
+        # Check if the pk of the model is UUID type and convert it to a string
+        if isinstance(message_body['pk'], UUID):
+            message_body.update({'pk': str(message_body['pk'])})
+
         message = dict(
             type=self.func.__name__.replace("_", "."),
             body=message_body,