diff --git a/src/sc_sacd.cpp b/src/sc_sacd.cpp
index 2713cdc..7f6a218 100644
--- a/src/sc_sacd.cpp
+++ b/src/sc_sacd.cpp
@@ -296,6 +296,12 @@ int SC_SACD_Sphere_Box_Collision(const SC_SACD_Sphere *sphere,
   SC_SACD_Vec3 sphere_pos{sphere->x, sphere->y, sphere->z};
   SC_SACD_Vec3 sphere_box_normal =
       SC_SACD_Vec3{box->x, box->y, box->z} - sphere_pos;
+  if (sphere_box_normal.x < 0.0001F && sphere_box_normal.x > -0.0001F &&
+      sphere_box_normal.y < 0.0001F && sphere_box_normal.y > -0.0001F &&
+      sphere_box_normal.z < 0.0001F && sphere_box_normal.z > -0.0001F) {
+    // Sphere center is box center.
+    return 1;
+  }
   sphere_box_normal =
       sphere_box_normal /
       std::sqrt(SC_SACD_Dot_Product(sphere_box_normal, sphere_box_normal));