diff --git a/tests/backend/mongodb/test_queries.py b/tests/backend/mongodb/test_queries.py
index 113f4249..eeb70399 100644
--- a/tests/backend/mongodb/test_queries.py
+++ b/tests/backend/mongodb/test_queries.py
@@ -529,7 +529,7 @@ def test_get_assets():
     assert list(cursor.sort('id', pymongo.ASCENDING)) == assets[::2]
 
 
-@pytest.mark.parametrize("table", ['assets', 'metadata'])
+@pytest.mark.parametrize('table', ['assets', 'metadata'])
 def test_text_search(table):
     from bigchaindb.backend import connect, query
     conn = connect()
diff --git a/tests/web/test_info.py b/tests/web/test_info.py
index c0728485..459f3e05 100644
--- a/tests/web/test_info.py
+++ b/tests/web/test_info.py
@@ -18,7 +18,7 @@ def test_api_root_endpoint(client, wsserver_base_url):
                 'outputs': '/api/v1/outputs/',
                 'streams': '{}/api/v1/streams/valid_transactions'.format(
                     wsserver_base_url),
-                "metadata": "/api/v1/metadata/"
+                'metadata': '/api/v1/metadata/',
             }
         },
         'docs': 'https://docs.bigchaindb.com/projects/server/en/vtsttst/',
@@ -42,7 +42,7 @@ def test_api_v1_endpoint(client, wsserver_base_url):
         'outputs': '/outputs/',
                 'streams': '{}/api/v1/streams/valid_transactions'.format(
                     wsserver_base_url),
-        "metadata": "/metadata/"
+        'metadata': '/metadata/',
     }
     res = client.get('/api/v1')
     assert res.json == api_v1_info
diff --git a/tests/web/test_transactions.py b/tests/web/test_transactions.py
index ab01357a..990173c5 100644
--- a/tests/web/test_transactions.py
+++ b/tests/web/test_transactions.py
@@ -47,8 +47,8 @@ def test_post_create_transaction_endpoint(b, client):
     assert res.json['outputs'][0]['public_keys'][0] == user_pub
 
 
-@pytest.mark.parametrize("nested", [False, True])
-@pytest.mark.parametrize("language,expected_status_code", [
+@pytest.mark.parametrize('nested', [False, True])
+@pytest.mark.parametrize('language,expected_status_code', [
     ('danish', 202), ('dutch', 202), ('english', 202), ('finnish', 202),
     ('french', 202), ('german', 202), ('hungarian', 202), ('italian', 202),
     ('norwegian', 202), ('portuguese', 202), ('romanian', 202), ('none', 202),
@@ -88,8 +88,8 @@ def test_post_create_transaction_with_language(b, client, nested, language,
             assert res.json['message'] == expected_error_message
 
 
-@pytest.mark.parametrize("field", ['asset', 'metadata'])
-@pytest.mark.parametrize("value,err_key,expected_status_code", [
+@pytest.mark.parametrize('field', ['asset', 'metadata'])
+@pytest.mark.parametrize('value,err_key,expected_status_code', [
     ({'bad.key': 'v'}, 'bad.key', 400),
     ({'$bad.key': 'v'}, '$bad.key', 400),
     ({'$badkey': 'v'}, '$badkey', 400),