diff --git a/src/libslic3r/TreeModelVolumes.cpp b/src/libslic3r/TreeModelVolumes.cpp
index 5a1fcec561..3c82b5c6c2 100644
--- a/src/libslic3r/TreeModelVolumes.cpp
+++ b/src/libslic3r/TreeModelVolumes.cpp
@@ -34,6 +34,8 @@ using namespace std::literals;
 // had to use a define beacuse the macro processing inside macro BOOST_LOG_TRIVIAL()
 #define error_level_not_in_cache error
 
+static constexpr const bool polygons_strictly_simple = false;
+
 TreeSupportMeshGroupSettings::TreeSupportMeshGroupSettings(const PrintObject &print_object)
 {
     const PrintConfig       &print_config       = print_object.print()->config();
@@ -175,7 +177,7 @@ TreeModelVolumes::TreeModelVolumes(
         tbb::parallel_for(tbb::blocked_range<size_t>(num_raft_layers, num_layers, std::min<size_t>(1, std::max<size_t>(16, num_layers / (8 * tbb::this_task_arena::max_concurrency())))),
             [&](const tbb::blocked_range<size_t> &range) {
             for (size_t layer_idx = range.begin(); layer_idx < range.end(); ++ layer_idx)
-                outlines[layer_idx] = to_polygons(expolygons_simplify(print_object.get_layer(layer_idx - num_raft_layers)->lslices, mesh_settings.resolution));
+                outlines[layer_idx] = polygons_simplify(to_polygons(print_object.get_layer(layer_idx - num_raft_layers)->lslices), mesh_settings.resolution, polygons_strictly_simple);
         });
     }
 #endif
@@ -585,7 +587,7 @@ void TreeModelVolumes::calculateCollision(const coord_t radius, const LayerIndex
                         if (processing_last_mesh) {
                             if (! dst.empty())
                                 collisions = union_(collisions, dst);
-                            dst = polygons_simplify(collisions, min_resolution);
+                            dst = polygons_simplify(collisions, min_resolution, polygons_strictly_simple);
                         } else
                             append(dst, std::move(collisions));
                         throw_on_cancel();
@@ -609,7 +611,7 @@ void TreeModelVolumes::calculateCollision(const coord_t radius, const LayerIndex
                         if (processing_last_mesh) {
                             if (! dst.empty())
                                 placable = union_(placable, dst);
-                            dst = polygons_simplify(placable, min_resolution);
+                            dst = polygons_simplify(placable, min_resolution, polygons_strictly_simple);
                         } else
                             append(dst, placable);
                         throw_on_cancel();
@@ -657,7 +659,7 @@ void TreeModelVolumes::calculateCollisionHolefree(const std::vector<RadiusLayerP
                     data.emplace_back(RadiusLayerPair(radius, layer_idx), polygons_simplify(
                         offset(union_ex(this->getCollision(m_increase_until_radius, layer_idx, false)),
                             5 - increase_radius_ceil, ClipperLib::jtRound, m_min_resolution),
-                        m_min_resolution));
+                        m_min_resolution, polygons_strictly_simple));
                     throw_on_cancel();
                 }
         }
@@ -744,7 +746,7 @@ void TreeModelVolumes::calculateAvoidance(const std::vector<RadiusLayerPair> &ke
                             ClipperLib::jtRound, m_min_resolution));
                 if (task.to_model)
                     latest_avoidance = diff(latest_avoidance, getPlaceableAreas(task.radius, layer_idx, throw_on_cancel));
-                latest_avoidance = polygons_simplify(latest_avoidance, m_min_resolution);
+                latest_avoidance = polygons_simplify(latest_avoidance, m_min_resolution, polygons_strictly_simple);
                 data.emplace_back(RadiusLayerPair{task.radius, layer_idx}, latest_avoidance);
                 throw_on_cancel();
             }
@@ -865,12 +867,12 @@ void TreeModelVolumes::calculateWallRestrictions(const std::vector<RadiusLayerPa
                     data[layer_idx - min_layer_bottom] = polygons_simplify(
                         // radius contains m_current_min_xy_dist_delta already if required
                         intersection(getCollision(0, layer_idx, false), getCollision(radius, layer_idx - 1, true)),
-                        m_min_resolution);
+                        m_min_resolution, polygons_strictly_simple);
                     if (! data_min.empty())
                         data_min[layer_idx - min_layer_bottom] = 
                             polygons_simplify(
                                 intersection(getCollision(0, layer_idx, true), getCollision(radius, layer_idx - 1, true)),
-                                m_min_resolution);
+                                m_min_resolution, polygons_strictly_simple);
                     throw_on_cancel();
                 }
             });