diff --git a/src/libslic3r/MultiMaterialSegmentation.cpp b/src/libslic3r/MultiMaterialSegmentation.cpp
index 03f326821..6428ab456 100644
--- a/src/libslic3r/MultiMaterialSegmentation.cpp
+++ b/src/libslic3r/MultiMaterialSegmentation.cpp
@@ -1575,7 +1575,7 @@ static inline std::vector<std::vector<ExPolygons>> mmu_segmentation_top_and_bott
                             append(triangles_by_color_top[color_idx][layer_idx + layer_idx_offset], top_ex);
                             float offset = 0.f;
                             ExPolygons layer_slices_trimmed = input_expolygons[layer_idx];
-                            for (int last_idx = int(layer_idx) - 1; last_idx >= std::max(int(layer_idx - stat.top_shell_layers), int(0)); --last_idx) {
+                            for (int last_idx = int(layer_idx) - 1; last_idx > std::max(int(layer_idx - stat.top_shell_layers), int(0)); --last_idx) {
                                 //BBS: offset width should be 2*spacing to avoid too narrow area which has overlap of wall line
                                 //offset -= stat.extrusion_width ;
                                 offset -= (stat.extrusion_spacing + stat.extrusion_width);