diff --git a/src/TreeSupport.cpp b/src/TreeSupport.cpp
index ead27ed820..8268bc2e9c 100644
--- a/src/TreeSupport.cpp
+++ b/src/TreeSupport.cpp
@@ -2023,7 +2023,7 @@ void TreeSupport::filterFloatingLines(std::vector<Shape>& support_layer_storage)
                 return;
             }
 
-            Shape relevant_forbidden = volumes_.getCollision(0, layer_idx, true);
+            const Shape& relevant_forbidden = volumes_.getCollision(0, layer_idx, true);
             Shape outer_walls = TreeSupportUtils::toPolylines(support_layer_storage[layer_idx - 1].getOutsidePolygons()).createTubeShape(closing_dist, 0);
 
             Shape holes_below;