diff --git a/thewalrus/tests/test_internal_modes.py b/thewalrus/tests/test_internal_modes.py
index d9e96187..7653c57f 100644
--- a/thewalrus/tests/test_internal_modes.py
+++ b/thewalrus/tests/test_internal_modes.py
@@ -1533,18 +1533,19 @@ def test_unknown_method_in_density_matrix_single_mode():
     with pytest.raises(ValueError, match="Unknown method for density_matrix_single_mode"):
         density_matrix_single_mode(cov, N, cutoff=cutoff, normalize=True, method="Coo coo ca choo")
 
+
 def test_haf_blocked():
     """Tests that haf blocked is the sum of many hafnians"""
     n = 6
-    B = np.random.rand(n,n)+ 1j*np.random.rand(n,n)
+    B = np.random.rand(n, n) + 1j * np.random.rand(n, n)
     A = B + B.T
-    reps_list = [[i, 3-i,4] for i in range(4)]
+    reps_list = [[i, 3 - i, 4] for i in range(4)]
     haf_sum = 0j
     for reps in reps_list:
         repreps = reps + reps
         haf = hafnian(reduction(A, repreps))
         haf_sum += haf / np.product(factorial(reps))
-    blocks = ((0,1),(2,))
-    repeats = (3,4)
-    haf_val = haf_blocked(A, blocks=blocks, repeats=repeats)/np.product(factorial(repeats))
+    blocks = ((0, 1), (2,))
+    repeats = (3, 4)
+    haf_val = haf_blocked(A, blocks=blocks, repeats=repeats) / np.product(factorial(repeats))
     assert np.allclose(haf_sum, haf_val)