diff --git a/docs/tracing_ext-demo.py b/docs/tracing_ext-demo.py
index b8f4663..306edd1 100644
--- a/docs/tracing_ext-demo.py
+++ b/docs/tracing_ext-demo.py
@@ -1,4 +1,5 @@
 """Tracing extension demo."""
+
 import time
 
 import pandas as pd
diff --git a/pandas_flavor/__init__.py b/pandas_flavor/__init__.py
index 554fee8..6d508d3 100644
--- a/pandas_flavor/__init__.py
+++ b/pandas_flavor/__init__.py
@@ -1,4 +1,5 @@
 """Top-level API for pandas-flavor."""
+
 from .register import (
     register_dataframe_accessor,
     register_dataframe_method,
diff --git a/pandas_flavor/__version__.py b/pandas_flavor/__version__.py
index 33da4ae..145fc03 100644
--- a/pandas_flavor/__version__.py
+++ b/pandas_flavor/__version__.py
@@ -1,2 +1,3 @@
 """Version number."""
+
 __version__ = "0.6.0"
diff --git a/pandas_flavor/register.py b/pandas_flavor/register.py
index 24d9ed0..e51ba6b 100644
--- a/pandas_flavor/register.py
+++ b/pandas_flavor/register.py
@@ -1,4 +1,5 @@
 """Register functions as methods of Pandas DataFrame and Series."""
+
 from functools import wraps
 from pandas.api.extensions import (
     register_series_accessor,
diff --git a/pandas_flavor/xarray.py b/pandas_flavor/xarray.py
index e3e990f..1c36a66 100644
--- a/pandas_flavor/xarray.py
+++ b/pandas_flavor/xarray.py
@@ -1,4 +1,5 @@
 """XArray support for pandas_flavor."""
+
 from xarray import register_dataarray_accessor, register_dataset_accessor
 from functools import wraps
 
diff --git a/setup.py b/setup.py
index 6e6a0e1..f9569c1 100644
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,5 @@
 """Setup script."""
+
 import io
 import os
 import sys
diff --git a/tests/test_pandas_register.py b/tests/test_pandas_register.py
index 5237db5..6b6cbe4 100644
--- a/tests/test_pandas_register.py
+++ b/tests/test_pandas_register.py
@@ -1,4 +1,5 @@
 """Tests for pandas series and dataframe method registration."""
+
 import pandas_flavor as pf
 import pandas as pd