diff --git a/swh/indexer/tests/storage/__init__.py b/swh/indexer/tests/storage/__init__.py
index 73a6f7a..436b176 100644
--- a/swh/indexer/tests/storage/__init__.py
+++ b/swh/indexer/tests/storage/__init__.py
@@ -1,89 +1,89 @@
 # Copyright (C) 2018  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
 
 from os import path
 import swh.storage
 
 from hypothesis.strategies import (binary, composite, sets, one_of,
                                    tuples, sampled_from)
 
 
 SQL_DIR = path.join(path.dirname(swh.indexer.__file__), 'sql')
 
 
-MIMETYPES = {
-    b'text/plain',
-    b'application/xml',
+MIMETYPES = [
     b'application/json',
     b'application/octet-stream',
-}
+    b'application/xml',
+    b'text/plain',
+]
 
-ENCODINGS = {
-    b'utf-8',
-    b'latin1',
+ENCODINGS = [
     b'iso8859-1',
     b'iso8859-15',
-}
+    b'latin1',
+    b'utf-8',
+]
 
 
 def gen_content_id():
     """Generate raw id strategy.
 
     """
     return binary(min_size=20, max_size=20)
 
 
 def gen_mimetype():
     """Generate one mimetype strategy.
 
     """
     return one_of(sampled_from(MIMETYPES))
 
 
 def gen_encoding():
     """Generate one encoding strategy.
 
     """
     return one_of(sampled_from(ENCODINGS))
 
 
 @composite
 def gen_content_mimetypes(draw, *, min_size=0, max_size=100):
     """Generate valid and consistent content_mimetypes.
 
     Context: Test purposes
 
     Args:
         **draw** (callable): Used by hypothesis to generate data
         **min_size** (int): Minimal number of elements to generate
                             (default: 0)
         **max_size** (int): Maximal number of elements to generate
                             (default: 100)
 
     Returns:
         List of content_mimetypes as expected by the
         content_mimetype_add api endpoint.
 
     """
     _ids = draw(
         sets(
             tuples(
                 gen_content_id(),
                 gen_mimetype(),
                 gen_encoding()
             ),
             min_size=min_size, max_size=max_size
         )
     )
 
     mimetypes = []
     for content_id, mimetype, encoding in _ids:
         mimetypes.append({
             'id': content_id,
             'mimetype': mimetype,
             'encoding': encoding,
             'indexer_configuration_id': 1,
         })
     return mimetypes