diff --git a/swh/objstorage/cloud/objstorage_azure.py b/swh/objstorage/cloud/objstorage_azure.py
index 0c62e31..6175738 100644
--- a/swh/objstorage/cloud/objstorage_azure.py
+++ b/swh/objstorage/cloud/objstorage_azure.py
@@ -1,85 +1,88 @@
 # Copyright (C) 2016  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import gzip
 
 from swh.core import hashutil
 from swh.objstorage.objstorage import ObjStorage, compute_hash
 from swh.objstorage.exc import ObjNotFoundError, Error
 
 from azure.storage.blob import BlockBlobService
+from azure.common import AzureMissingResourceHttpError
 
 
 class AzureCloudObjStorage(ObjStorage):
     """ObjStorage with azure abilities
 
     """
     def __init__(self, account_name, api_secret_key, container_name):
         self.block_blob_service = BlockBlobService(
             account_name=account_name,
             account_key=api_secret_key)
         self.container_name = container_name
 
     def __contains__(self, obj_id):
         hex_obj_id = hashutil.hash_to_hex(obj_id)
         return self.block_blob_service.exists(
             container_name=self.container_name,
             blob_name=hex_obj_id)
 
     def __iter__(self):
         """ Iterate over the objects present in the storage
 
         """
         for obj in self.block_blob_service.list_blobs(self.container_name):
             yield obj.name
 
     def __len__(self):
         """Compute the number of objects in the current object storage.
 
         Returns:
             number of objects contained in the storage.
 
         """
         return sum(1 for i in self)
 
     def add(self, content, obj_id=None, check_presence=True):
         """Add an obj in storage if it's not there already.
 
         """
         if obj_id is None:
             # Checksum is missing, compute it on the fly.
             obj_id = compute_hash(content)
 
         if check_presence and obj_id in self:
             return obj_id
 
         hex_obj_id = hashutil.hash_to_hex(obj_id)
 
         # Send the gzipped content
         self.block_blob_service.create_blob_from_bytes(
             container_name=self.container_name,
             blob_name=hex_obj_id,
             blob=gzip.compress(content))
 
         return obj_id
 
     def restore(self, content, obj_id=None):
         return self.add(content, obj_id, check_presence=False)
 
     def get(self, obj_id):
         hex_obj_id = hashutil.hash_to_hex(obj_id)
-        blob = self.block_blob_service.get_blob_to_bytes(
-            container_name=self.container_name,
-            blob_name=hex_obj_id)
-        if not blob:
+        try:
+            blob = self.block_blob_service.get_blob_to_bytes(
+                container_name=self.container_name,
+                blob_name=hex_obj_id)
+        except AzureMissingResourceHttpError:
             raise ObjNotFoundError('Content %s not found!' % hex_obj_id)
+
         return gzip.decompress(blob.content)
 
     def check(self, obj_id):
         # Check the content integrity
         obj_content = self.get(obj_id)
         content_obj_id = compute_hash(obj_content)
         if content_obj_id != obj_id:
             raise Error(obj_id)
diff --git a/swh/objstorage/tests/test_objstorage_azure.py b/swh/objstorage/tests/test_objstorage_azure.py
index cfd2b56..afbe955 100644
--- a/swh/objstorage/tests/test_objstorage_azure.py
+++ b/swh/objstorage/tests/test_objstorage_azure.py
@@ -1,60 +1,64 @@
 # Copyright (C) 2016  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import unittest
 
+from azure.common import AzureMissingResourceHttpError
+
 from swh.objstorage.cloud.objstorage_azure import AzureCloudObjStorage
 
 from objstorage_testing import ObjStorageTestFixture
 
 
 class MockBlob():
     """ Libcloud object mock that replicates its API """
     def __init__(self, name, content):
         self.name = name
         self.content = content
 
 
 class MockBlockBlobService():
     """Mock internal azure library which AzureCloudObjStorage depends upon.
 
     """
     data = {}
 
     def __init__(self, account_name, api_secret_key, container_name):
         # do not care for the account_name and the api_secret_key here
         self.data[container_name] = {}
 
     def create_blob_from_bytes(self, container_name, blob_name, blob):
         self.data[container_name][blob_name] = blob
 
     def get_blob_to_bytes(self, container_name, blob_name):
         if blob_name not in self.data[container_name]:
-            return None
+            raise AzureMissingResourceHttpError(
+                'Blob %s not found' % blob_name,
+                404)
         return MockBlob(name=blob_name,
                         content=self.data[container_name][blob_name])
 
     def exists(self, container_name, blob_name):
         return blob_name in self.data[container_name]
 
     def list_blobs(self, container_name):
         for blob_name, content in self.data[container_name].items():
             yield MockBlob(name=blob_name, content=content)
 
 
 class MockAzureCloudObjStorage(AzureCloudObjStorage):
     """ Cloud object storage that uses a mocked driver """
     def __init__(self, api_key, api_secret_key, container_name):
         self.container_name = container_name
         self.block_blob_service = MockBlockBlobService(api_key, api_secret_key,
                                                        container_name)
 
 
 class TestAzureCloudObjStorage(ObjStorageTestFixture, unittest.TestCase):
 
     def setUp(self):
         super().setUp()
         self.storage = MockAzureCloudObjStorage(
             'account-name', 'api-secret-key', 'container-name')