diff --git a/tests/test_constraints.py b/tests/test_constraints.py
index 71150543..fa7b7ba2 100644
--- a/tests/test_constraints.py
+++ b/tests/test_constraints.py
@@ -14,11 +14,10 @@
 import os
 import re
 
-from pyomo.repn.tests.lp_diff import lp_diff
-
 import oemof.solph as solph
 import pandas as pd
 from oemof.solph import helpers
+from pyomo.repn.tests.lp_diff import lp_diff
 
 from oemof.thermal import facades