diff --git a/src/pymatgen/analysis/local_env.py b/src/pymatgen/analysis/local_env.py
index ab077294b6e..66f9ea9f222 100644
--- a/src/pymatgen/analysis/local_env.py
+++ b/src/pymatgen/analysis/local_env.py
@@ -4095,12 +4095,12 @@ def _quadrant_integral(dist_bins, idx):
 
         areaquarter = 0.25 * math.pi * radius**2
 
-        area1 = areaquarter - 0.5 * (radius**2 * math.acos(
-            1 - x1 / radius) - (radius - x1) * math.sqrt(
-            2 * radius * x1 - x1**2))
-        area2 = areaquarter - 0.5 * (radius**2 * math.acos(
-            1 - x2 / radius) - (radius - x2) * math.sqrt(
-            2 * radius * x2 - x2**2))
+        area1 = areaquarter - 0.5 * (
+            radius**2 * math.acos(1 - x1 / radius) - (radius - x1) * math.sqrt(2 * radius * x1 - x1**2)
+        )
+        area2 = areaquarter - 0.5 * (
+            radius**2 * math.acos(1 - x2 / radius) - (radius - x2) * math.sqrt(2 * radius * x2 - x2**2)
+        )
 
         return (area2 - area1) / areaquarter
 
diff --git a/tests/analysis/test_local_env.py b/tests/analysis/test_local_env.py
index 4a1f9679a8c..92c31b85e55 100644
--- a/tests/analysis/test_local_env.py
+++ b/tests/analysis/test_local_env.py
@@ -444,10 +444,8 @@ def test_all_nn_classes(self):
         assert voronoi_nn.get_cn(self.cscl, 0) == 8
         assert voronoi_nn.get_cn(self.lifepo4, 0) == 6
 
-        assert CrystalNN._quadrant_integral([1,0.36], 0) == approx(
-            0.7551954297486029)
-        assert CrystalNN._quadrant_integral([1,0.36,0], 1) == approx(
-            1 - 0.7551954297486029)
+        assert CrystalNN._quadrant_integral([1, 0.36], 0) == approx(0.7551954297486029)
+        assert CrystalNN._quadrant_integral([1, 0.36, 0], 1) == approx(1 - 0.7551954297486029)
         crystal_nn = CrystalNN()
         assert crystal_nn.get_cn(self.diamond, 0) == 4
         assert crystal_nn.get_cn(self.nacl, 0) == 6