1 files changed, 3 insertions, 1 deletions
diff --git a/source/blender/blenlib/intern/mesh_boolean.cc b/source/blender/blenlib/intern/mesh_boolean.cc
index bad0b84d10f..8b6a7ed65f7 100644
--- a/source/blender/blenlib/intern/mesh_boolean.cc
+++ b/source/blender/blenlib/intern/mesh_boolean.cc
@@ -428,7 +428,9 @@ class Cell {
                                         BoolOpType bool_optype)
   {
     std::copy(from_cell.winding().begin(), from_cell.winding().end(), winding_.begin());
-    winding_[shape] += delta;
+    if (shape >= 0) {
+      winding_[shape] += delta;
+    }
     winding_assigned_ = true;
     in_output_volume_ = apply_bool_op(bool_optype, winding_);
   }