diff --git a/force_bdss/cli/tests/test_execution.py b/force_bdss/cli/tests/test_execution.py
index 1311a92dad32fedd02449b4bf21f49b1b037fd1b..3202beee1ddbe86d1e31833a86a09ae16770b554 100644
--- a/force_bdss/cli/tests/test_execution.py
+++ b/force_bdss/cli/tests/test_execution.py
@@ -26,16 +26,19 @@ class TestExecution(unittest.TestCase):
     def test_plain_invocation_mco(self):
         with cd(fixtures.dirpath()):
             try:
-                subprocess.check_output(["force_bdss", "test_empty.json"])
+                subprocess.check_output(["force_bdss", "test_empty.json"],
+                                        stderr=subprocess.STDOUT)
             except subprocess.CalledProcessError:
                 self.fail("force_bdss returned error at plain invocation.")
 
     def test_plain_invocation_evaluate(self):
-        with cd(fixtures.dirpath()):
+        with cd(fixtures.dirpath()), \
+                open(os.devnull, "wb") as devnull:
             proc = subprocess.Popen([
                 "force_bdss", "--evaluate", "test_empty.json"],
                 stdin=subprocess.PIPE,
-                stdout=subprocess.PIPE)
+                stdout=subprocess.PIPE,
+                stderr=devnull)
             proc.communicate(b"1")
             retcode = proc.wait()
             self.assertEqual(retcode, 0)
diff --git a/force_bdss/core_evaluation_driver.py b/force_bdss/core_evaluation_driver.py
index 2657f3565d378eb07bb1acf960fb0b60674bd1f5..96a717383b1d019a225e99f315e37c06cb99d2be 100644
--- a/force_bdss/core_evaluation_driver.py
+++ b/force_bdss/core_evaluation_driver.py
@@ -14,6 +14,7 @@ CORE_EVALUATION_DRIVER_ID = plugin_id("core", "CoreEvaluationDriver")
 
 log = logging.getLogger(__name__)
 
+
 class CoreEvaluationDriver(BaseCoreDriver):
     """Main plugin that handles the execution of the MCO
     or the evaluation.