diff --git a/etrago/cluster/gas.py b/etrago/cluster/gas.py
index ee3b68e4..fd7916a5 100644
--- a/etrago/cluster/gas.py
+++ b/etrago/cluster/gas.py
@@ -26,12 +26,12 @@
 if "READTHEDOCS" not in os.environ:
     import logging
 
-    from pypsa.components import Network
     from pypsa.clustering.spatial import (
         aggregatebuses,
         aggregateoneport,
         busmap_by_kmeans,
     )
+    from pypsa.components import Network
     from six import iteritems
     import numpy as np
     import pandas as pd