diff --git a/cloud_storage_handler/api/elixircloud/csh/client.py b/cloud_storage_handler/api/elixircloud/csh/client.py
index 634ff5a..a5941e7 100644
--- a/cloud_storage_handler/api/elixircloud/csh/client.py
+++ b/cloud_storage_handler/api/elixircloud/csh/client.py
@@ -1,7 +1,6 @@
 """MinIO client class and convenience functions."""
 
 import logging
-from typing import Type
 
 from connexion import FlaskApp
 from minio import Minio
@@ -28,7 +27,7 @@ def __init__(self, config: MinioConfig) -> None:
             config: MinIO configuration.
         """
         self.config: MinioConfig = config
-        self.client: Type[Minio] = Minio(
+        self.client: Minio = Minio(
             endpoint=f"{config.hostname}:{config.port}",
             access_key=config.access_key,
             secret_key=config.secret_key,
@@ -48,14 +47,14 @@ def register_minio_client(app: FlaskApp) -> FlaskApp:
     """Register MinIO client and create bucket.
 
     Args:
-        app: FOCA app instance.
+        app: Connexion Flask app instance.
 
     Returns:
-        FOCA app instance with MinIO client instance added to config.
+        Connexion Flask app instance with a MinIO client instance added to
+            its config.
     """
-    minio_config = app.app.config.foca.custom.minio
-    minio_client = MinioClient(config=minio_config)
+    minio_client = MinioClient(config=app.app.config.foca.custom.minio)
     minio_client.create_bucket()
-    minio_config.client = minio_client
+    app.app.config.foca.custom.minio.client = minio_client
     logger.info("MinIO client registered.")
     return app
diff --git a/cloud_storage_handler/api/elixircloud/csh/models.py b/cloud_storage_handler/api/elixircloud/csh/models.py
index ffced88..5508c56 100644
--- a/cloud_storage_handler/api/elixircloud/csh/models.py
+++ b/cloud_storage_handler/api/elixircloud/csh/models.py
@@ -1,6 +1,6 @@
 """Model for MinIO Configuration."""
 
-from typing import Annotated, Optional, Type
+from typing import Annotated, Optional
 
 from minio import Minio
 from pydantic import BaseModel, conint, constr
@@ -37,4 +37,9 @@ class MinioConfig(BaseModel):
     secret_key: str = "minioadmin"
     bucket_name: Annotated[str, constr(min_length=1)] = "files"
     secure: bool = False
-    client: Optional[Type[Minio]] = None
+    client: Optional[Minio] = None
+
+    class Config:
+        """Model configuration."""
+
+        arbitrary_types_allowed = True
diff --git a/cloud_storage_handler/main.py b/cloud_storage_handler/main.py
index fa1a957..d54bba7 100644
--- a/cloud_storage_handler/main.py
+++ b/cloud_storage_handler/main.py
@@ -19,7 +19,7 @@ def init_app() -> FlaskApp:
     the default path if not.
 
     Returns:
-        A Connexion application instance.
+        A Connexion Flask application instance.
     """
     config_path = Path(
         os.getenv(