diff --git a/xs/src/libslic3r/ExPolygon.cpp b/xs/src/libslic3r/ExPolygon.cpp
index bfc3d5077a0..d1cc295611b 100644
--- a/xs/src/libslic3r/ExPolygon.cpp
+++ b/xs/src/libslic3r/ExPolygon.cpp
@@ -212,7 +212,7 @@ ExPolygon::remove_point_too_near(const coord_t tolerance) {
 void
 ExPolygon::medial_axis(const ExPolygon &bounds, double max_width, double min_width, ThickPolylines* polylines, double height, bool stop_at_min_width) const {
     Slic3r::MedialAxis ma(*this, bounds, max_width, min_width, height);
-	ma.stop_at_min_width = stop_at_min_width;
+    ma.stop_at_min_width = stop_at_min_width;
     ma.build(polylines);
 }
 
diff --git a/xs/src/libslic3r/MedialAxis.cpp b/xs/src/libslic3r/MedialAxis.cpp
index 2cd602db1fb..f5de2b49dfa 100644
--- a/xs/src/libslic3r/MedialAxis.cpp
+++ b/xs/src/libslic3r/MedialAxis.cpp
@@ -301,13 +301,14 @@ remove_point_too_near(ThickPolyline* to_reduce)
             to_reduce->points.erase(to_reduce->points.begin() + id);
             to_reduce->width.erase(to_reduce->width.begin() + id);
             newdist = to_reduce->points[id].distance_to(to_reduce->points[id - 1]);
+            //if you removed a point, it check if the next one isn't too near from the previous one.
+            // if not, it bypass it.
+            if (newdist > smallest) {
+                ++id;
+            }
         }
         //go to next one
-        //if you removed a point, it check if the next one isn't too near from the previous one.
-        // if not, it byepass it.
-        if (newdist > smallest) {
-            ++id;
-        }
+        else ++id;
     }
 }
 
@@ -620,7 +621,7 @@ MedialAxis::extends_line(ThickPolyline& polyline, const ExPolygons& anchors, con
             line.a = *(polyline.points.begin() + first_idx);
         }
         // prevent the line from touching on the other side, otherwise intersection() might return that solution
-        if (polyline.points.size() == 2) line.a = line.midpoint();
+        if (polyline.points.size() == 2 && this->expolygon.contains(line.midpoint())) line.a = line.midpoint();
 
         line.extend_end(max_width);
         Point new_back;
@@ -628,18 +629,37 @@ MedialAxis::extends_line(ThickPolyline& polyline, const ExPolygons& anchors, con
             new_back = polyline.points.back();
         } else {
             //TODO: verify also for holes.
-            (void)this->expolygon.contour.first_intersection(line, &new_back);
+            bool finded = this->expolygon.contour.first_intersection(line, &new_back);
+            //verify also for holes.
+            Point new_back_temp;
+            for (Polygon hole : this->expolygon.holes) {
+                if (hole.first_intersection(line, &new_back_temp)) {
+                    if (!finded || line.a.distance_to(new_back_temp) < line.a.distance_to(new_back)) {
+                        finded = true;
+                        new_back = new_back_temp;
+                    }
+                }
+            }
             // safety check if no intersection
-            if (new_back.x == 0 && new_back.y == 0) new_back = line.b;
+            if (!finded) new_back = line.b;
 
             polyline.points.push_back(new_back);
             polyline.width.push_back(polyline.width.back());
         }
         Point new_bound;
-        //TODO: verify also for holes.
-        (void)bounds.contour.first_intersection(line, &new_bound);
+        bool finded = bounds.contour.first_intersection(line, &new_bound);
+        //verify also for holes.
+        Point new_bound_temp;
+        for (Polygon hole : bounds.holes) {
+            if (hole.first_intersection(line, &new_bound_temp)) {
+                if (!finded || line.a.distance_to(new_bound_temp) < line.a.distance_to(new_bound)) {
+                    finded = true;
+                    new_bound = new_bound_temp;
+                }
+            }
+        }
         // safety check if no intersection
-        if (new_bound.x == 0 && new_bound.y == 0) {
+        if (!finded) {
             if (line.b.coincides_with_epsilon(polyline.points.back())) return;
             //check if we don't over-shoot inside us
             bool is_in_anchor = false;
@@ -1363,7 +1383,7 @@ MedialAxis::build(ThickPolylines* polylines_out)
     // Loop through all returned polylines in order to extend their endpoints to the 
     //   expolygon boundaries (if done here, it may be cut later if not thick enough)
     if (stop_at_min_width) {
-		const ExPolygons anchors = offset2_ex(to_polygons(diff_ex(this->bounds, this->expolygon)), -SCALED_RESOLUTION, SCALED_RESOLUTION);
+        const ExPolygons anchors = offset2_ex(to_polygons(diff_ex(this->bounds, this->expolygon)), -SCALED_RESOLUTION, SCALED_RESOLUTION);
         for (size_t i = 0; i < pp.size(); ++i) {
             ThickPolyline& polyline = pp[i];
             extends_line(polyline, anchors, min_width);
@@ -1398,14 +1418,14 @@ MedialAxis::build(ThickPolylines* polylines_out)
     // Loop through all returned polylines in order to extend their endpoints to the 
     //   expolygon boundaries
     if (!stop_at_min_width) {
-		const ExPolygons anchors = offset2_ex(to_polygons(diff_ex(this->bounds, this->expolygon)), -SCALED_RESOLUTION, SCALED_RESOLUTION);
-		for (size_t i = 0; i < pp.size(); ++i) {
-			ThickPolyline& polyline = pp[i];
-			extends_line(polyline, anchors, min_width);
-			polyline.reverse();
-			extends_line(polyline, anchors, min_width);
-		}
-	}
+        const ExPolygons anchors = offset2_ex(to_polygons(diff_ex(this->bounds, this->expolygon)), -SCALED_RESOLUTION, SCALED_RESOLUTION);
+        for (size_t i = 0; i < pp.size(); ++i) {
+            ThickPolyline& polyline = pp[i];
+            extends_line(polyline, anchors, min_width);
+            polyline.reverse();
+            extends_line(polyline, anchors, min_width);
+        }
+    }
     //{
     //    stringstream stri;
     //    stri << "medial_axis_5_expand_" << id << ".svg";
diff --git a/xs/src/libslic3r/MedialAxis.hpp b/xs/src/libslic3r/MedialAxis.hpp
index 3ec9d467d27..25a2c15f781 100644
--- a/xs/src/libslic3r/MedialAxis.hpp
+++ b/xs/src/libslic3r/MedialAxis.hpp
@@ -17,7 +17,7 @@ namespace Slic3r {
     public:
         Lines lines; //lines is here only to avoid appassing it in argument of amny method. Initialized in polyline_from_voronoi.
         ExPolygon expolygon;
-		
+        
         const ExPolygon& surface;
         const ExPolygon& bounds;
         const double max_width;
diff --git a/xs/src/libslic3r/PerimeterGenerator.cpp b/xs/src/libslic3r/PerimeterGenerator.cpp
index 681a10f451b..87a1bb66975 100644
--- a/xs/src/libslic3r/PerimeterGenerator.cpp
+++ b/xs/src/libslic3r/PerimeterGenerator.cpp
@@ -133,6 +133,7 @@ PerimeterGenerator::process()
                         if (half_thins.size() > 0) {
                             no_thin_zone = diff(last, to_polygons(offset_ex(half_thins, (float)(min_width / 2) - SCALED_EPSILON)), true);
                         }
+                        ExPolygons thin_zones_extruded;
                         // compute a bit of overlap to anchor thin walls inside the print.
                         for (ExPolygon &half_thin : half_thins) {
                             //growing back the polygon
@@ -145,17 +146,20 @@ PerimeterGenerator::process()
                             for (ExPolygon &bound : bounds) {
                                 if (!intersection_ex(thin[0], bound).empty()) {
                                     //be sure it's not too small to extrude reliably
-									thin[0].remove_point_too_near(SCALED_RESOLUTION);
+                                    thin[0].remove_point_too_near(SCALED_RESOLUTION);
                                     if (thin[0].area() > min_width*(ext_pwidth + ext_pspacing2)) {
-										bound.remove_point_too_near(SCALED_RESOLUTION);
+                                        bound.remove_point_too_near(SCALED_RESOLUTION);
                                         // the maximum thickness of our thin wall area is equal to the minimum thickness of a single loop
                                         thin[0].medial_axis(bound, ext_pwidth + ext_pspacing2, min_width,
                                             &thin_walls, this->layer_height);
+                                        thin_zones_extruded.emplace_back(thin[0]);
                                     }
                                     break;
                                 }
                             }
                         }
+                        // recompute the next onion, to be sure to not miss any small areas that can't be extruded by thin_walls
+                        offsets = diff_ex(offset_ex(last, -(float)(ext_perimeter_width / 2)), thin_zones_extruded, true);
                         #ifdef DEBUG
                         printf("  %zu thin walls detected\n", thin_walls.size());
                         #endif