diff --git a/tests/conftest.py b/tests/conftest.py
index 532e22d..6d1889b 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -19,6 +19,7 @@
 """Configuration of pytest."""
 
 import pytest
+
 from tinydft.basis import Basis
 from tinydft.grid import setup_grid
 
diff --git a/tests/test_tinybasis.py b/tests/test_tinybasis.py
index fe6a25f..e957c07 100644
--- a/tests/test_tinybasis.py
+++ b/tests/test_tinybasis.py
@@ -23,6 +23,7 @@
 from numpy.testing import assert_allclose
 from scipy.linalg import eigh
 from test_tinygrid import get_hydrogenic_solutions
+
 from tinydft.basis import Basis
 from tinydft.grid import setup_grid
 
diff --git a/tests/test_tinydft.py b/tests/test_tinydft.py
index bc0725a..8b2629b 100644
--- a/tests/test_tinydft.py
+++ b/tests/test_tinydft.py
@@ -21,6 +21,7 @@
 import numpy as np
 import pytest
 from numpy.testing import assert_allclose
+
 from tinydft.atom import char2angqn, interpret_econf, klechkowski
 from tinydft.dft import build_rho, scf_atom, solve_poisson
 from tinydft.grid import setup_grid
diff --git a/tests/test_tinygrid.py b/tests/test_tinygrid.py
index 12766dd..80842bd 100644
--- a/tests/test_tinygrid.py
+++ b/tests/test_tinygrid.py
@@ -23,6 +23,7 @@
 from numpy.polynomial.legendre import legval
 from numpy.testing import assert_allclose
 from scipy.special import eval_genlaguerre, factorial
+
 from tinydft.grid import LegendreGrid, TransformedGrid