diff --git a/tests/test_key_handling/test_key_derivation/test_tree.py b/tests/test_key_handling/test_key_derivation/test_tree.py
index 9b3463f..d0bb5d3 100644
--- a/tests/test_key_handling/test_key_derivation/test_tree.py
+++ b/tests/test_key_handling/test_key_derivation/test_tree.py
@@ -1,6 +1,7 @@
 import os
 import json
 from py_ecc.bls import G2ProofOfPossession as bls
+import pytest
 
 
 from eth2deposit.key_handling.key_derivation.tree import (
@@ -25,7 +26,6 @@ def test_hkdf_mod_r(test) -> None:
     assert bls.KeyGen(seed) == _HKDF_mod_r(IKM=seed)
 
 
-
 @pytest.mark.parametrize(
     'test',
     test_vectors