diff --git a/src/libslic3r/ContourZ.cpp b/src/libslic3r/ContourZ.cpp
index 8eb1a8b5a8..48a3da13c3 100644
--- a/src/libslic3r/ContourZ.cpp
+++ b/src/libslic3r/ContourZ.cpp
@@ -63,10 +63,14 @@ static bool contour_extrusion_path(LayerRegion *region, const sla::IndexedMesh &
 		int num_segments = int(std::ceil(length_mm / resolution_mm));
 		Vec2d delta = line.vector();
 
-		for (int i = 0; i < num_segments+1; i++) {
-			Vec2d p = p1d + delta*i/num_segments;
+        if (num_segments == 0) {
+            continue;
+        }
 
-			coordf_t x = p.x();
+        for (int i = 0; i < num_segments + 1; i++) {
+            Vec2d p = p1d + delta * i / num_segments;
+
+            coordf_t x = p.x();
 			coordf_t y = p.y();
 
 			sla::IndexedMesh::hit_result hit_up = mesh.query_ray_hit({x, y, mesh_z}, {0.0, 0.0, 1.0});
@@ -116,24 +120,22 @@ static bool contour_extrusion_path(LayerRegion *region, const sla::IndexedMesh &
 				was_contoured = true;
 			}
 
-			Vec3d new_point = {p.x(), p.y(), d};
+            Vec3d new_point = {p.x(), p.y(), d};
 
-			if (contoured_points.size() > 2) {
-				double dist = Linef3::distance_to_infinite_squared(
-					contoured_points[contoured_points.size() - 2], 
-					contoured_points[contoured_points.size() - 1], 
-					new_point);
-				if (dist < EPSILON) {
-					contoured_points[contoured_points.size() - 1] = new_point;
-					continue;
-				}
-			}
+            if (contoured_points.size() >= 2) {
+                double dist = Linef3::distance_to_infinite_squared(new_point, contoured_points[contoured_points.size() - 2],
+                                                                   contoured_points[contoured_points.size() - 1]);
+                if (dist < EPSILON * EPSILON) {
+                    contoured_points[contoured_points.size() - 1] = new_point;
+                    continue;
+                }
+            }
 
-			contoured_points.push_back(new_point);
-		}
-	}
+            contoured_points.push_back(new_point);
+        }
+    }
 
-	if (!was_contoured) {
+    if (!was_contoured) {
 		return false;
 	}
 
diff --git a/src/libslic3r/GCode.cpp b/src/libslic3r/GCode.cpp
index 3693ffa872..39ac5b4d83 100644
--- a/src/libslic3r/GCode.cpp
+++ b/src/libslic3r/GCode.cpp
@@ -6760,10 +6760,8 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                         if (z < 0.1) {
                             throw RuntimeError("GCode: very low z");
                         }
-                        gcode += m_writer.extrude_to_xyz(
-                            Vec3d(dest2d.x(), dest2d.y(), z),
-                            e,
-                            tempDescription + "; z_diff " + std::to_string(z_diff) + " " + ExtrusionEntity::role_to_string(path.role()) + "; eratio " + std::to_string(extrusion_ratio));
+                        gcode += m_writer.extrude_to_xyz(Vec3d(dest2d.x(), dest2d.y(), z), e,
+                                                         GCodeWriter::full_gcode_comment ? tempDescription : "");
 
                     } else if (sloped == nullptr) {
                         // Normal extrusion
diff --git a/src/libslic3r/PrintObject.cpp b/src/libslic3r/PrintObject.cpp
index 5dd342eaf9..e4d47c065e 100644
--- a/src/libslic3r/PrintObject.cpp
+++ b/src/libslic3r/PrintObject.cpp
@@ -732,7 +732,8 @@ void PrintObject::contour_z()
     ModelInstance *inst = m_model_object->instances.front();
     Point                    center_offset = this->center_offset();
     Geometry::Transformation trans = inst->get_transformation();
-    double                   z             = trans.get_offset().z() - unscale<double>(this->height()) / 2;
+
+    double z = this->m_model_object->min_z();
     trans.set_offset(Vec3d(-unscale<double>(center_offset.x()), -unscale<double>(center_offset.y()), 0));
     mesh.transform(trans.get_matrix());