diff --git a/frustum.c b/frustum.c
index f50865f..e8975e8 100644
--- a/frustum.c
+++ b/frustum.c
@@ -53,6 +53,15 @@ void frustum_update(int width, int height)
     //     left.vx, left.pad, right.vx, right.pad, top.vz, top.pad, bottom.vz, bottom.pad);
 }
 
+static INLINE u_char frustum_pointInside_(const SVECTOR p)
+{
+    if (m_dot12(left, p) + left.pad < 0) return 0;
+    if (m_dot12(right, p) + right.pad < 0) return 0;
+    if (m_dot12(top, p) + top.pad < 0) return 0;
+    if (m_dot12(bottom, p) + bottom.pad < 0) return 0;
+    return 1;
+}
+
 u_char frustum_pointInside(const SVECTOR *point)
 {
     if (m_dot12(left, *point) + left.pad < 0) return 0;
@@ -71,3 +80,16 @@ u_char frustum_sphereInside(const SVECTOR *sphere)
     if (m_dot12(bottom, *sphere) + bottom.pad < radius) return 0;
     return 1;
 }
+
+u_char frustum_boxInside(const SVECTOR *min, const SVECTOR *max)
+{
+    if (frustum_pointInside_((SVECTOR) { min->vx, min->vy, min->vz })) return 1;
+    if (frustum_pointInside_((SVECTOR) { min->vx, min->vy, max->vz })) return 1;
+    if (frustum_pointInside_((SVECTOR) { min->vx, max->vy, min->vz })) return 1;
+    if (frustum_pointInside_((SVECTOR) { min->vx, max->vy, max->vz })) return 1;
+    if (frustum_pointInside_((SVECTOR) { max->vx, min->vy, min->vz })) return 1;
+    if (frustum_pointInside_((SVECTOR) { max->vx, min->vy, max->vz })) return 1;
+    if (frustum_pointInside_((SVECTOR) { max->vx, max->vy, min->vz })) return 1;
+    if (frustum_pointInside_((SVECTOR) { max->vx, max->vy, max->vz })) return 1;
+    return 0;
+}
diff --git a/frustum.h b/frustum.h
index 244502d..c9e0796 100644
--- a/frustum.h
+++ b/frustum.h
@@ -4,5 +4,6 @@
 void frustum_update(int width, int height);
 u_char frustum_pointInside(const SVECTOR *point);
 u_char frustum_sphereInside(const SVECTOR *sphere);
+u_char frustum_boxInside(const SVECTOR *min, const SVECTOR *max);
 
 #endif  // __FRUSTUM_H__
diff --git a/ps1bsp.h b/ps1bsp.h
index d9bd4c6..17c3513 100755
--- a/ps1bsp.h
+++ b/ps1bsp.h
@@ -138,18 +138,18 @@ typedef struct
 	SVECTOR boundingSphere;
 } ps1bsp_node_t;
 
-typedef struct
+typedef struct ps1bsp_leaf_s
 {
-	int type;
+	short type;
 	int vislist;
 
-	SVECTOR boundingSphere;
+	SVECTOR mins, maxs;
 
 	u_short firstLeafFace;
 	u_short numLeafFaces;
 
 	// Run-time data
-	u_short nextLeaf;	// For chaining leafs in drawing order
+	struct ps1bsp_leaf_s *nextLeaf;	// For chaining leafs in drawing order
 	u_short leafDepth;	// At what depth the leaf's faces should be placed in the ordering table
 } ps1bsp_leaf_t;
 
diff --git a/test.ps1bsp b/test.ps1bsp
index 60d25db..8c18893 100755
Binary files a/test.ps1bsp and b/test.ps1bsp differ
diff --git a/world.c b/world.c
index 262e70c..31139e2 100644
--- a/world.c
+++ b/world.c
@@ -200,7 +200,7 @@ static void world_drawnode(const world_t *world, short nodeIdx, u_char *pvs)
             return;
 
         const ps1bsp_leaf_t *leaf = &world->leaves[~nodeIdx];
-        // if (!frustum_sphereInside(&leaf->boundingSphere))    // TODO: not sure if it's actually faster to do all these additional frustum checks
+        // if (!frustum_boxInside(&leaf->mins, &leaf->maxs))   // TODO: these additional frustum checks actually make things slower, probably not worth it
         //     return;
 
         u_long frameNum = time_getFrameNumber();