diff --git a/README.md b/README.md
index 36e810d..f0bd139 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # Django Base Settings
 
-[![Latest Release](https://img.shields.io/github/v/release/vsakkas/django-base-settings.svg?color=187f58)](https://github.com/vsakkas/django-base-settings/releases/tag/v0.3.0)
+[![Latest Release](https://img.shields.io/github/v/release/vsakkas/django-base-settings.svg?color=187f58)](https://github.com/vsakkas/django-base-settings/releases/tag/v0.4.0)
 [![Python](https://img.shields.io/badge/python-3.10+-187f58.svg)](https://www.python.org/downloads/)
 [![Django Version](https://img.shields.io/badge/django-5.0+-187f58)](https://www.djangoproject.com/)
 [![MIT License](https://img.shields.io/badge/license-MIT-187f58)](https://github.com/vsakkas/django-base-settings/blob/master/LICENSE)
diff --git a/django_base_settings/django_base_settings.py b/django_base_settings/django_base_settings.py
index 097a6cd..0bc050d 100644
--- a/django_base_settings/django_base_settings.py
+++ b/django_base_settings/django_base_settings.py
@@ -7,12 +7,14 @@
 
 
 class BaseModel(_BaseModel):
-    model_config = ConfigDict(alias_generator=lambda field_name: field_name.upper())
+    model_config = ConfigDict(
+        alias_generator=lambda field_name: field_name.upper(), frozen=True
+    )
 
 
 class BaseSettings(_BaseSettings):
     model_config = SettingsConfigDict(
-        alias_generator=lambda field_name: field_name.upper()
+        alias_generator=lambda field_name: field_name.upper(), frozen=True
     )
 
 
diff --git a/pyproject.toml b/pyproject.toml
index f137109..e48e48f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "django-base-settings"
-version = "0.3.0"
+version = "0.4.0"
 description = "Use Pydantic to enhance your Django application settings."
 authors = ["vsakkas <vasileios.sakkas96@gmail.com>"]
 license = "MIT"