diff --git a/reana_client/cli/cwl_runner.py b/reana_client/cli/cwl_runner.py
index f6fd8940..eec09716 100644
--- a/reana_client/cli/cwl_runner.py
+++ b/reana_client/cli/cwl_runner.py
@@ -173,7 +173,6 @@ def cwl_runner(ctx, quiet, outdir, basedir, processfile, jobfile, access_token):
             response = get_workflow_logs(workflow_id, access_token)
             logs = response["logs"]
             if logs != first_logs:
-
                 logging.error(logs[len(first_logs) :])
                 first_logs = logs
 
diff --git a/reana_client/utils.py b/reana_client/utils.py
index d4ad5443..b8596bf2 100644
--- a/reana_client/utils.py
+++ b/reana_client/utils.py
@@ -138,6 +138,7 @@ def get_workflow_duration(workflow: Dict) -> Optional[int]:
     :return: The duration of the workflow in seconds or ``None`` if the starting
         time is not present.
     """
+
     # FIXME: Use datetime.fromisoformat when moving to Python 3.7 or higher
     def fromisoformat(date_string):
         return datetime.strptime(date_string, "%Y-%m-%dT%H:%M:%S")
diff --git a/tests/test_cli_ping.py b/tests/test_cli_ping.py
index b30ff039..0ec7da7b 100644
--- a/tests/test_cli_ping.py
+++ b/tests/test_cli_ping.py
@@ -64,7 +64,6 @@ def test_ping_ok():
             "reana_client.api.client.current_rs_api_client",
             make_mock_api_client("reana-server")(mock_response, mock_http_response),
         ):
-
             result = runner.invoke(cli, ["ping", "-t", reana_token])
             message = "Authenticated as: John Doe <johndoe@example.org>"
             assert message in result.output