diff --git a/src/libslic3r/Support/TreeSupport.cpp b/src/libslic3r/Support/TreeSupport.cpp
index c4c01c3399..914a0ed667 100644
--- a/src/libslic3r/Support/TreeSupport.cpp
+++ b/src/libslic3r/Support/TreeSupport.cpp
@@ -1033,18 +1033,20 @@ void TreeSupport::detect_overhangs(bool check_support_necessity/* = false*/)
             }
         }
 
+        if (layer_nr < blockers.size()) {
+            // Arthur: union_ is a must because after mirroring, the blocker polygons are in left-hand coordinates, ie clockwise, 
+            // which are not valid polygons, and will be removed by offset_ex. union_ can make these polygons right.
+            ExPolygons blocker = offset_ex(union_(blockers[layer_nr]), scale_(radius_sample_resolution));
+            layer->loverhangs = diff_ex(layer->loverhangs, blocker);
+            layer->cantilevers = diff_ex(layer->cantilevers, blocker);
+            sharp_tail_overhangs = diff_ex(sharp_tail_overhangs, blocker);
+        }
+
         if (support_critical_regions_only && is_auto(stype)) {
             layer->loverhangs.clear();  // remove oridinary overhangs, only keep cantilevers and sharp tails (added later)
             append(layer->loverhangs, layer->cantilevers);
         }
 
-        if (layer_nr < blockers.size()) {
-            Polygons& blocker = blockers[layer_nr];
-            // Arthur: union_ is a must because after mirroring, the blocker polygons are in left-hand coordinates, ie clockwise, 
-            // which are not valid polygons, and will be removed by offset_ex. union_ can make these polygons right.
-            layer->loverhangs = diff_ex(layer->loverhangs, offset_ex(union_(blocker), scale_(radius_sample_resolution)));
-        }
-
         if (max_bridge_length > 0 && layer->loverhangs.size() > 0 && lower_layer) {
             // do not break bridge for normal part in TreeHybrid, nor Tree Strong
             bool break_bridge = !(m_support_params.support_style == smsTreeHybrid && area(layer->loverhangs) > m_support_params.thresh_big_overhang)