diff --git a/src/libslic3r/PerimeterGenerator.cpp b/src/libslic3r/PerimeterGenerator.cpp
index 602190b5d..82cd96be3 100644
--- a/src/libslic3r/PerimeterGenerator.cpp
+++ b/src/libslic3r/PerimeterGenerator.cpp
@@ -605,22 +605,43 @@ void PerimeterGenerator::process()
                     else offset_top_surface = 0;
                     //don't takes into account too thin areas
                     double min_width_top_surface = std::max(double(ext_perimeter_spacing / 2 + 10), this->config->min_width_top_surface.get_abs_value(double(perimeter_width)));
-                    //make thin upper surfaces disapear with -+offset_top_surface becasue it will be harder to do so later, as they can merge together to form big blob
-                    const ExPolygons grown_upper_slices = offset2_ex(*this->upper_slices, -offset_top_surface, offset_top_surface+min_width_top_surface);
+                    //make thin upper surfaces disapear with -+offset_top_surface
+                    ExPolygons grown_upper_slices;
+                    //do offset2 per island, to avoid big blob merging
+                    //remove polygon too thin (but don't mess with holes)
+                    for (const ExPolygon& expoly_to_grow : *this->upper_slices) {
+                        //only offset the contour, as it can merge holes
+                        Polygons contour = offset2({ expoly_to_grow.contour }, -offset_top_surface, offset_top_surface + min_width_top_surface + (have_to_grow_for_miller ? (double)mill_extra_size : 0));
+                        if (!contour.empty()) {
+                            if (expoly_to_grow.holes.empty()) {
+                                for (Polygon& p : contour)
+                                    grown_upper_slices.push_back(ExPolygon{ p });
+                            } else {
+                                Polygons holes = expoly_to_grow.holes;
+                                for (Polygon& h : holes)
+                                    h.reverse();
+                                holes = offset(holes, -min_width_top_surface - (have_to_grow_for_miller ? (double)mill_extra_size : 0));
+                                for (ExPolygon p : diff_ex(contour, holes))
+                                    grown_upper_slices.push_back(p);
+                            }
+                        }
+                    }
+                    grown_upper_slices = union_ex(grown_upper_slices);
                     //set the clip to a virtual "second perimeter"
                     fill_clip = offset_ex(last, -double(ext_perimeter_spacing));
+                    auto fill_clip_old = fill_clip;
                     // get the real top surface
                     const ExPolygons top_grown_polygons = (!have_to_grow_for_miller) 
                         ? diff_ex(last, grown_upper_slices, true)
                         :(unmillable.empty())
-                                ? diff_ex(last, offset_ex(grown_upper_slices, (double)mill_extra_size), true)
-                                : diff_ex(last, diff_ex(offset_ex(grown_upper_slices, (double)mill_extra_size), unmillable, true));
-
+                                ? diff_ex(last, grown_upper_slices, true)
+                                : diff_ex(last, diff_ex(grown_upper_slices, unmillable, true));
 
                     //get the not-top surface, from the "real top" but enlarged by external_infill_margin (and the min_width_top_surface we removed a bit before)
-                    const ExPolygons inner_polygons = diff_ex(last, offset_ex(top_grown_polygons, offset_top_surface + min_width_top_surface
-                        //also remove the ext_perimeter_spacing/2 width because we are faking the external periemter, and we will remove ext_perimeter_spacing2
-                        - double(ext_perimeter_spacing / 2)), true);
+                    const ExPolygons inner_polygons = diff_ex(last, 
+                        offset_ex(top_grown_polygons, offset_top_surface + min_width_top_surface
+                            //also remove the ext_perimeter_spacing/2 width because we are faking the external periemter, and we will remove ext_perimeter_spacing2
+                            - double(ext_perimeter_spacing / 2)), true);
                     // get the enlarged top surface, by using inner_polygons instead of upper_slices, and clip it for it to be exactly the polygons to fill.
                     const ExPolygons top_polygons = diff_ex(fill_clip, inner_polygons, true);
                     // increase by half peri the inner space to fill the frontier between last and stored.
@@ -629,17 +650,17 @@ void PerimeterGenerator::process()
                     double infill_spacing_unscaled = this->config->infill_extrusion_width.get_abs_value(nozzle_diameter);
                     if (infill_spacing_unscaled == 0) infill_spacing_unscaled = Flow::auto_extrusion_width(frInfill, nozzle_diameter);
                     fill_clip = offset_ex(last, double(ext_perimeter_spacing / 2) - scale_d(infill_spacing_unscaled / 2));
-                    // ExPolygons oldLast = last;
                     last = intersection_ex(inner_polygons, last);
                     //{
                     //    std::stringstream stri;
                     //    stri << this->layer->id() << "_1_"<< i <<"_only_one_peri"<< ".svg";
                     //    SVG svg(stri.str());
-                    //    svg.draw(to_polylines(top_fills), "green");
+                    //    svg.draw(to_polylines(oldLast), "orange");
+                    //    svg.draw(to_polylines(fill_clip), "purple");
                     //    svg.draw(to_polylines(inner_polygons), "yellow");
                     //    svg.draw(to_polylines(top_polygons), "cyan");
-                    //    svg.draw(to_polylines(oldLast), "orange");
                     //    svg.draw(to_polylines(last), "red");
+                    //    svg.draw(to_polylines(fill_clip_old), "green");
                     //    svg.Close();
                     //}
                 }