diff --git a/attachment_s3/models/ir_attachment.py b/attachment_s3/models/ir_attachment.py
index e573b98b..b39f60e0 100644
--- a/attachment_s3/models/ir_attachment.py
+++ b/attachment_s3/models/ir_attachment.py
@@ -181,6 +181,7 @@ def _store_file_read(self, fname, bin_size=False):
     @api.model
     def _store_file_write(self, key, bin_data):
         location = self.env.context.get('storage_location') or self._storage()
+        mimetype = self.env.context.get('mimetype')
         if location == 's3':
             bucket = self._get_s3_bucket()
             obj = bucket.Object(key=key)
@@ -189,7 +190,10 @@ def _store_file_write(self, key, bin_data):
                 file.seek(0)
                 filename = 's3://%s/%s' % (bucket.name, key)
                 try:
-                    obj.upload_fileobj(file)
+                    if mimetype:
+                        obj.upload_fileobj(file, ExtraArgs={'Metadata': {'ContentType': mimetype}})
+                    else:
+                        obj.upload_fileobj(file)
                 except ClientError as error:
                     # log verbose error from s3, return short message for user
                     _logger.exception(
diff --git a/base_attachment_object_storage/models/ir_attachment.py b/base_attachment_object_storage/models/ir_attachment.py
index 0a3ecfa2..1ef2a8ae 100644
--- a/base_attachment_object_storage/models/ir_attachment.py
+++ b/base_attachment_object_storage/models/ir_attachment.py
@@ -164,6 +164,10 @@ def _store_in_db_instead_of_object_storage(self):
                 return len(bin_data) <= limit
         return False
 
+    def _get_datas_related_values(self, data, mimetype):
+        self=self.with_context(mimetype=mimetype)
+        return super(IrAttachment, self)._get_datas_related_values(data, mimetype)
+
     def _inverse_datas(self):
         # override in order to store files that need fast access,
         # we keep them in the database instead of the object storage