diff --git a/include/qbsp/brush.hh b/include/qbsp/brush.hh
index 737c1be3..1ed37dbc 100644
--- a/include/qbsp/brush.hh
+++ b/include/qbsp/brush.hh
@@ -61,7 +61,7 @@ struct bspbrush_t
      * the BrushBSP will have this pointing back to the original brush in the list.
      */
     bspbrush_t *original;
-    const mapbrush_t *mapbrush;
+    mapbrush_t *mapbrush;
     uint32_t file_order;
     aabb3d bounds;
     int side, testside; // side of node during construction
@@ -80,5 +80,5 @@ struct bspbrush_t
 
 using bspbrush_vector_t = std::vector<std::unique_ptr<bspbrush_t>>;
 
-std::optional<bspbrush_t> LoadBrush(const mapentity_t *src, const mapbrush_t *mapbrush, const contentflags_t &contents, const int hullnum);
+std::optional<bspbrush_t> LoadBrush(const mapentity_t *src, mapbrush_t *mapbrush, const contentflags_t &contents, const int hullnum);
 bool CreateBrushWindings(bspbrush_t *brush);
\ No newline at end of file
diff --git a/include/qbsp/qbsp.hh b/include/qbsp/qbsp.hh
index 1d961c96..dda7cf1f 100644
--- a/include/qbsp/qbsp.hh
+++ b/include/qbsp/qbsp.hh
@@ -626,11 +626,6 @@ struct bspbrush_t;
 struct side_t;
 class mapbrush_t;
 
-struct bspbrush_t_less
-{
-    bool operator()(const bspbrush_t *a, const bspbrush_t *b) const;
-};
-
 struct node_t
 {
     // both leafs and nodes
@@ -666,8 +661,7 @@ struct node_t
     uint32_t firstleafbrush; // Q2
     uint32_t numleafbrushes;
     int32_t area;
-    std::vector<bspbrush_t *> original_brushes; // FIXME: only valid during construction
-    std::vector<const mapbrush_t *> original_mapbrushes;
+    std::vector<bspbrush_t *> original_brushes;
 };
 
 void InitQBSP(int argc, const char **argv);
diff --git a/qbsp/brush.cc b/qbsp/brush.cc
index 3bc46f70..ad3f6b99 100644
--- a/qbsp/brush.cc
+++ b/qbsp/brush.cc
@@ -28,11 +28,6 @@
 #include <qbsp/map.hh>
 #include <qbsp/qbsp.hh>
 
-bool bspbrush_t_less::operator()(const bspbrush_t *a, const bspbrush_t *b) const
-{
-    return a->file_order < b->file_order;
-}
-
 const maptexinfo_t &side_t::get_texinfo() const
 {
     return map.mtexinfos[this->texinfo];
@@ -256,7 +251,7 @@ LoadBrush
 Converts a mapbrush to a bsp brush
 ===============
 */
-std::optional<bspbrush_t> LoadBrush(const mapentity_t *src, const mapbrush_t *mapbrush, const contentflags_t &contents,
+std::optional<bspbrush_t> LoadBrush(const mapentity_t *src, mapbrush_t *mapbrush, const contentflags_t &contents,
     const int hullnum)
 {
     // create the brush
@@ -352,7 +347,7 @@ std::optional<bspbrush_t> LoadBrush(const mapentity_t *src, const mapbrush_t *ma
 
 //=============================================================================
 
-static void Brush_LoadEntity(mapentity_t *dst, const mapentity_t *src, const int hullnum, content_stats_base_t &stats, bspbrush_vector_t &brushes)
+static void Brush_LoadEntity(mapentity_t *dst, mapentity_t *src, const int hullnum, content_stats_base_t &stats, bspbrush_vector_t &brushes)
 {
     // _omitbrushes 1 just discards all brushes in the entity.
     // could be useful for geometry guides, selective compilation, etc.
diff --git a/qbsp/map.cc b/qbsp/map.cc
index 55eb1b06..44732d81 100644
--- a/qbsp/map.cc
+++ b/qbsp/map.cc
@@ -192,7 +192,7 @@ static qvec2f projectToAxisPlane(const qvec3d &snapped_normal, const qvec3d &poi
 static texdef_quake_ed_noshift_t Reverse_QuakeEd(qmat2x2f M, const qbsp_plane_t &plane, bool preserveX);
 static void SetTexinfo_QuakeEd_New(
     const qbsp_plane_t &plane, const qvec2d &shift, vec_t rotate, const qvec2d &scale, texvecf &out_vecs);
-static void TestExpandBrushes(const mapentity_t *src);
+static void TestExpandBrushes(mapentity_t *src);
 
 static void AddAnimTex(const char *name)
 {
@@ -2821,7 +2821,7 @@ allow visual inspection of the clipping bevels
 from q3map
 ================
 */
-static void TestExpandBrushes(const mapentity_t *src)
+static void TestExpandBrushes(mapentity_t *src)
 {
     std::vector<std::unique_ptr<bspbrush_t>> hull1brushes;
 
diff --git a/qbsp/outside.cc b/qbsp/outside.cc
index 626cd363..62a69608 100644
--- a/qbsp/outside.cc
+++ b/qbsp/outside.cc
@@ -414,6 +414,7 @@ static void MarkVisibleBrushSides_R(node_t *node)
             for (auto *brush : neighbour_leaf->original_brushes) {
                 for (auto &side : brush->sides) {
                     // fixme-brushbsp: should this be get_plane() ?
+                    // fixme-brushbsp: planenum 
                     if (qv::epsilonEqual(side.get_positive_plane(), portal->plane)) {
                         // we've found a brush side in an original brush in the neighbouring
                         // leaf, on a portal to this (non-opaque) leaf, so mark it as visible.
diff --git a/qbsp/qbsp.cc b/qbsp/qbsp.cc
index 68efe779..f2dc35ff 100644
--- a/qbsp/qbsp.cc
+++ b/qbsp/qbsp.cc
@@ -300,20 +300,20 @@ static void ExportBrushList_r(const mapentity_t *entity, node_t *node)
 {
     if (node->is_leaf) {
         if (node->contents.native) {
-            if (node->original_mapbrushes.size()) {
-                node->numleafbrushes = node->original_mapbrushes.size();
+            if (node->original_brushes.size()) {
+                node->numleafbrushes = node->original_brushes.size();
                 brush_state.total_leaf_brushes += node->numleafbrushes;
                 node->firstleafbrush = map.bsp.dleafbrushes.size();
-                for (auto &b : node->original_mapbrushes) {
+                for (auto &b : node->original_brushes) {
 
-                    if (!b->outputnumber.has_value()) {
+                    if (!b->mapbrush->outputnumber.has_value()) {
                         // FIXME
-                        const_cast<mapbrush_t *>(b)->outputnumber = {static_cast<uint32_t>(map.bsp.dbrushes.size())};
+                        b->mapbrush->outputnumber = {static_cast<uint32_t>(map.bsp.dbrushes.size())};
 
                         dbrush_t &brush = map.bsp.dbrushes.emplace_back(
                             dbrush_t{static_cast<int32_t>(map.bsp.dbrushsides.size()), 0, b->contents.native});
 
-                        for (auto &side : b->faces) {
+                        for (auto &side : b->mapbrush->faces) {
                             map.bsp.dbrushsides.push_back(
                                 {(uint32_t) ExportMapPlane(side.planenum), (int32_t)ExportMapTexinfo(side.texinfo)});
                             brush.numsides++;
@@ -323,7 +323,7 @@ static void ExportBrushList_r(const mapentity_t *entity, node_t *node)
                         brush_state.total_brushes++;
                     }
 
-                    map.bsp.dleafbrushes.push_back(b->outputnumber.value());
+                    map.bsp.dleafbrushes.push_back(b->mapbrush->outputnumber.value());
                 }
             }
         }
diff --git a/qbsp/tree.cc b/qbsp/tree.cc
index 2db2aba5..0195f1bd 100644
--- a/qbsp/tree.cc
+++ b/qbsp/tree.cc
@@ -78,24 +78,15 @@ void FreeTreePortals(tree_t *tree)
 static void ConvertNodeToLeaf(node_t *node, const contentflags_t &contents)
 {
     // merge the children's brush lists
-    node->original_brushes = std::move(node->children[0]->original_brushes);
-    node->original_brushes.insert(node->original_brushes.end(), node->children[1]->original_brushes.begin(), node->children[1]->original_brushes.end());
+    size_t base = node->children[0]->original_brushes.size() > node->children[1]->original_brushes.size() ? 0 : 1;
+    node->original_brushes = std::move(node->children[base]->original_brushes);
+    node->original_brushes.insert(node->original_brushes.end(), node->children[base ^ 1]->original_brushes.begin(), node->children[base ^ 1]->original_brushes.end());
 
-    if (node->original_brushes.size()) {
-        std::sort(node->original_brushes.begin(), node->original_brushes.end(), bspbrush_t_less());
-        auto unique_begin = std::unique(node->original_brushes.begin(), node->original_brushes.end());
-        node->original_brushes.erase(unique_begin, node->original_brushes.end());
-
-        // migrate it over to mapbrushes
-        node->original_mapbrushes.reserve(node->original_brushes.size());
-
-        for (auto &b : node->original_brushes) {
-            node->original_mapbrushes.push_back(b->mapbrush);
-        }
-
-        // clear original_brushes since we no longer need it
-        node->original_brushes.clear();
-    }
+    std::sort(node->original_brushes.begin(), node->original_brushes.end(), [](const bspbrush_t *a, const bspbrush_t *b) {
+        return a->file_order < b->file_order;
+    });
+    auto unique = std::unique(node->original_brushes.begin(), node->original_brushes.end());
+    node->original_brushes.erase(unique, node->original_brushes.end());
 
     node->is_leaf = true;
 
@@ -127,8 +118,6 @@ static void PruneNodes_R(node_t *node, std::atomic<int32_t> &count_pruned)
         // This discards any faces on-node. Should be safe (?)
         ConvertNodeToLeaf(node, qbsp_options.target_game->create_solid_contents());
         ++count_pruned;
-    } else {
-        node->original_brushes.clear();
     }
 
     // DarkPlaces has an assertion that fails if both children are