diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index c61d3a3f95..aef379d225 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -1,7 +1,7 @@
 from abc import ABC, abstractmethod
 from copy import copy
 from math import sqrt
-from numpy import array
+import numpy as np
 
 import openmc
 from openmc.checkvalue import check_greater_than, check_value
@@ -88,9 +88,9 @@ class IsogonalOctagon(CompositeSurface):
         Top planar surface of octagon
     bottom : openmc.ZPlane, openmc.XPlane, or openmc.YPlane
         Bottom planar surface of octagon
-    right: openmc.YPlane, openmc.ZPlane, or openmc.XPlane
+    right : openmc.YPlane, openmc.ZPlane, or openmc.XPlane
         Right planar surface of octagon
-    left: openmc.YPlane, openmc.ZPlane, or openmc.XPlane
+    left : openmc.YPlane, openmc.ZPlane, or openmc.XPlane
         Left planar surface of octagon
     upper_right : openmc.Plane
         Upper right planar surface of octagon
@@ -126,17 +126,16 @@ class IsogonalOctagon(CompositeSurface):
             raise ValueError(f'r1 is greater than sqrt(2) * r2. Octagon' + \
                              ' may be erroneous.')
 
-        L_perp_ax1 = (r2 * sqrt(2) - r1) * 2
-        L_perp_ax2 = (r1 * sqrt(2) - r2) * 2
+        L_perp_ax1 = (r2 * sqrt(2) - r1)
 
         # Coords for quadrant planes
-        p1_ur = array([L_perp_ax1/2, r1, 0.])
-        p2_ur = array([r1, L_perp_ax1/2, 0.])
-        p3_ur = array([r1, L_perp_ax1/2, 1.])
+        p1_ur = np.array([L_perp_ax1, r1, 0.])
+        p2_ur = np.array([r1, L_perp_ax1, 0.])
+        p3_ur = np.array([r1, L_perp_ax1, 1.])
 
-        p1_lr = array([r1, -L_perp_ax1/2, 0.])
-        p2_lr = array([L_perp_ax1/2, -r1, 0.])
-        p3_lr = array([L_perp_ax1/2, -r1, 1.])
+        p1_lr = np.array([r1, -L_perp_ax1, 0.])
+        p2_lr = np.array([L_perp_ax1, -r1, 0.])
+        p3_lr = np.array([L_perp_ax1, -r1, 1.])
 
         points = [p1_ur, p2_ur, p3_ur, p1_lr, p2_lr, p3_lr]
 
diff --git a/tests/unit_tests/test_surface_composite.py b/tests/unit_tests/test_surface_composite.py
index 3595c59e67..20670efcdb 100644
--- a/tests/unit_tests/test_surface_composite.py
+++ b/tests/unit_tests/test_surface_composite.py
@@ -191,10 +191,10 @@ def test_isogonal_octagon(axis, plane_tb, plane_lr, axis_idx):
 
     # Check bounding box
     center = np.insert(center, axis_idx, np.inf)
-    xmax,ymax,zmax = center + r1
+    xmax, ymax, zmax = center + r1
     coord_min = center - r1
     coord_min[axis_idx] *= -1
-    xmin,ymin,zmin = coord_min
+    xmin, ymin, zmin = coord_min
     ll, ur = (+s).bounding_box
     assert np.all(np.isinf(ll))
     assert np.all(np.isinf(ur))