diff --git a/include/qbsp/csg.hh b/include/qbsp/csg.hh
index 41110e77..2fb1720f 100644
--- a/include/qbsp/csg.hh
+++ b/include/qbsp/csg.hh
@@ -36,3 +36,4 @@ std::unique_ptr<face_t> NewFaceFromFace(const face_t *in);
 std::unique_ptr<face_t> CopyFace(const face_t* in);
 std::tuple<std::unique_ptr<face_t>, std::unique_ptr<face_t>> SplitFace(std::unique_ptr<face_t> in, const qplane3d &split);
 void UpdateFaceSphere(face_t *in);
+std::vector<std::unique_ptr<bspbrush_t>> MakeBspBrushList(mapentity_t *entity);
diff --git a/qbsp/brushbsp.cc b/qbsp/brushbsp.cc
index a4949419..27b44cf0 100644
--- a/qbsp/brushbsp.cc
+++ b/qbsp/brushbsp.cc
@@ -970,15 +970,7 @@ static std::unique_ptr<tree_t> BrushBSP(mapentity_t *entity, std::vector<std::un
 
 std::unique_ptr<tree_t> BrushBSP(mapentity_t *entity, bool midsplit)
 {
-    // set the original pointers
-    std::vector<std::unique_ptr<bspbrush_t>> brushcopies;
-    for (const auto &original : entity->brushes) {
-        auto copy = original->copy_unique();
-        copy->original = original.get();
-        brushcopies.push_back(std::move(copy));
-    }
-
-    auto tree = BrushBSP(entity, std::move(brushcopies));
+    auto tree = BrushBSP(entity, MakeBspBrushList(entity));
 
     return tree;
 }
diff --git a/qbsp/csg.cc b/qbsp/csg.cc
index be2935e9..a6808d7f 100644
--- a/qbsp/csg.cc
+++ b/qbsp/csg.cc
@@ -123,3 +123,16 @@ std::tuple<std::unique_ptr<face_t>, std::unique_ptr<face_t>> SplitFace(std::uniq
 
     return {std::move(new_front), std::move(new_back)};
 }
+
+std::vector<std::unique_ptr<bspbrush_t>> MakeBspBrushList(mapentity_t *entity)
+{
+    // set the original pointers
+    std::vector<std::unique_ptr<bspbrush_t>> brushcopies;
+    for (const auto &original : entity->brushes) {
+        auto copy = original->copy_unique();
+        copy->original = original.get();
+        brushcopies.push_back(std::move(copy));
+    }
+
+    return brushcopies;
+}