diff --git a/zaqar/storage/swift/claims.py b/zaqar/storage/swift/claims.py
index ae7dc7605..b5e4ffbd6 100644
--- a/zaqar/storage/swift/claims.py
+++ b/zaqar/storage/swift/claims.py
@@ -119,6 +119,7 @@ class ClaimController(storage.Claim):
                     utils._message_container(queue, project),
                     msg['id'],
                     content,
+                    content_type='application/json',
                     headers={'x-object-meta-clientid': msg['client_uuid'],
                              'if-match': md5,
                              'x-object-meta-claimid': claim_id,
@@ -137,6 +138,7 @@ class ClaimController(storage.Claim):
             utils._claim_container(queue, project),
             claim_id,
             jsonutils.dumps([msg['id'] for msg in claimed]),
+            content_type='application/json',
             headers={'x-delete-after': ttl}
         )
 
@@ -152,6 +154,7 @@ class ClaimController(storage.Claim):
             raise
 
         self._client.put_object(container, claim_id, obj,
+                                content_type='application/json',
                                 headers={'x-delete-after': metadata['ttl']})
 
     def delete(self, queue, claim_id, project=None):
@@ -176,6 +179,7 @@ class ClaimController(storage.Claim):
                     utils._message_container(queue, project),
                     msg_id,
                     content,
+                    content_type='application/json',
                     headers={'x-object-meta-clientid': client_id,
                              'if-match': md5,
                              'x-delete-at': headers['x-delete-at']})
diff --git a/zaqar/storage/swift/messages.py b/zaqar/storage/swift/messages.py
index 3c5c2c817..f1ddb4666 100644
--- a/zaqar/storage/swift/messages.py
+++ b/zaqar/storage/swift/messages.py
@@ -220,6 +220,7 @@ class MessageController(storage.Message):
                 utils._message_container(queue, project),
                 slug,
                 contents=contents,
+                content_type='application/json',
                 headers={
                     'x-object-meta-clientid': str(client_uuid),
                     'x-delete-after': msg['ttl']})
diff --git a/zaqar/storage/swift/subscriptions.py b/zaqar/storage/swift/subscriptions.py
index cbc73d238..0058fed3d 100644
--- a/zaqar/storage/swift/subscriptions.py
+++ b/zaqar/storage/swift/subscriptions.py
@@ -98,7 +98,7 @@ class SubscriptionController(storage.Subscription):
                 'confirmed': False}
         utils._put_or_create_container(
             self._client, container, slug, contents=jsonutils.dumps(data),
-            headers={'x-delete-after': ttl})
+            content_type='application/json', headers={'x-delete-after': ttl})
         return slug
 
     def update(self, queue, subscription_id, project=None, **kwargs):
@@ -124,6 +124,7 @@ class SubscriptionController(storage.Subscription):
         self._client.put_object(container,
                                 subscription_id,
                                 contents=jsonutils.dumps(data),
+                                content_type='application/json',
                                 headers={'x-delete-after': ttl})
 
     def exists(self, queue, subscription_id, project=None):