diff --git a/znh5md/__init__.py b/znh5md/__init__.py
index d0afb65e..6a26787b 100644
--- a/znh5md/__init__.py
+++ b/znh5md/__init__.py
@@ -1,4 +1,5 @@
 """ZnH5MD: High Performance Interface for H5MD Trajectories."""
+
 import contextlib
 import importlib.metadata
 
diff --git a/znh5md/format/__init__.py b/znh5md/format/__init__.py
index 509bb6a6..24aa1511 100644
--- a/znh5md/format/__init__.py
+++ b/znh5md/format/__init__.py
@@ -1,4 +1,5 @@
 """Format handler for h5md files."""
+
 import contextlib
 import dataclasses
 import typing