diff --git a/tests/test_single_obs_key.py b/tests/test_single_obs_key.py
index 16e4a97..1a60346 100644
--- a/tests/test_single_obs_key.py
+++ b/tests/test_single_obs_key.py
@@ -1,7 +1,9 @@
 from ase.build import molecule
 from ase.calculators.singlepoint import SinglePointCalculator
+
 import znh5md
 
+
 def test_single_entry_info(tmp_path):
     # Test a special case where only the first config has the key
     # which caused an error in the past