diff --git a/src/libslic3r/Fill/Fill.cpp b/src/libslic3r/Fill/Fill.cpp
index 197fa20ede8..fa4476535d3 100644
--- a/src/libslic3r/Fill/Fill.cpp
+++ b/src/libslic3r/Fill/Fill.cpp
@@ -9803,20 +9803,20 @@ static bool top_surface_image_append_recolored_perimeter_path(ExtrusionEntitiesP
     };
 
     for (size_t point_idx = 1; point_idx < path.polyline.points.size(); ++point_idx) {
-        const Point &p0 = path.polyline.points[point_idx - 1];
-        const Point &p1 = path.polyline.points[point_idx];
-        const double len_mm = unscale<double>(p0.distance_to(p1));
+        const Point3 &p0 = path.polyline.points[point_idx - 1];
+        const Point3 &p1 = path.polyline.points[point_idx];
+        const double len_mm = unscale<double>(p0.to_point().distance_to(p1.to_point()));
         if (!std::isfinite(len_mm) || len_mm <= EPSILON)
             continue;
         const int steps = std::max(1, int(std::floor(len_mm / min_run_mm)));
         for (int step = 0; step < steps; ++step) {
             const double t0 = double(step) / double(steps);
             const double t1 = double(step + 1) / double(steps);
-            const Point q0 = lerp(p0, p1, t0);
-            const Point q1 = lerp(p0, p1, t1);
+            const Point q0 = lerp(p0, p1, t0).to_point();
+            const Point q1 = lerp(p0, p1, t1).to_point();
             if (q0 == q1)
                 continue;
-            const Point qm = lerp(p0, p1, 0.5 * (t0 + t1));
+            const Point qm = lerp(p0, p1, 0.5 * (t0 + t1)).to_point();
             int extruder_override = top_surface_image_perimeter_override_at_point(qm, masks);
             if (extruder_override >= 0 && len_mm / double(steps) < min_run_mm - EPSILON)
                 extruder_override = -1;
@@ -10864,20 +10864,20 @@ static ExtrusionPaths top_surface_image_split_path(const ExtrusionPath &path,
     for (size_t point_idx = 1; point_idx < path.polyline.points.size(); ++point_idx) {
         if ((point_idx & 63) == 1)
             check_canceled(throw_if_canceled);
-        const Point p0 = path.polyline.points[point_idx - 1];
-        const Point p1 = path.polyline.points[point_idx];
-        const double len_mm = unscale<double>(p0.distance_to(p1));
+        const Point3 p0 = path.polyline.points[point_idx - 1];
+        const Point3 p1 = path.polyline.points[point_idx];
+        const double len_mm = unscale<double>(p0.to_point().distance_to(p1.to_point()));
         if (!std::isfinite(len_mm) || len_mm <= EPSILON)
             continue;
         const int steps = std::max(1, int(std::ceil(len_mm / sample_step_mm)));
         for (int step = 0; step < steps; ++step) {
             const double t0 = double(step) / double(steps);
             const double t1 = double(step + 1) / double(steps);
-            const Point q0 = lerp(p0, p1, t0);
-            const Point q1 = lerp(p0, p1, t1);
+            const Point q0 = lerp(p0, p1, t0).to_point();
+            const Point q1 = lerp(p0, p1, t1).to_point();
             if (q0 == q1)
                 continue;
-            const Point qm = lerp(p0, p1, 0.5 * (t0 + t1));
+            const Point qm = lerp(p0, p1, 0.5 * (t0 + t1)).to_point();
             const std::vector<float> weights =
                 texture_mapping_offset_component_weights_at_point(context,
                                                                   unscale<float>(qm.x()),
diff --git a/src/libslic3r/Polyline.hpp b/src/libslic3r/Polyline.hpp
index 88671391db9..c14d6329e94 100644
--- a/src/libslic3r/Polyline.hpp
+++ b/src/libslic3r/Polyline.hpp
@@ -302,6 +302,8 @@ public:
 
     virtual Lines3 lines() const;
 
+    bool is_closed() const { return this->points.size() >= 2 && this->points.front() == this->points.back(); }
+
     // Convert to 2D Polyline by dropping Z coordinates
     Polyline to_polyline() const;