diff --git a/src/libslic3r/Format/3mf.cpp b/src/libslic3r/Format/3mf.cpp
index 698382c6f..845e982a9 100644
--- a/src/libslic3r/Format/3mf.cpp
+++ b/src/libslic3r/Format/3mf.cpp
@@ -676,7 +676,7 @@ namespace Slic3r {
                     // select the geometry associated with the original model object
                     const Geometry* geometry = nullptr;
                     for (const IdToModelObjectMap::value_type& object : m_objects) {
-                        if (static_cast<int>(object.second) == i) {
+                        if (object.second == int(i)) {
                             IdToGeometryMap::const_iterator obj_geometry = m_geometries.find(object.first);
                             if (obj_geometry == m_geometries.end()) {
                                 add_error("Unable to find object geometry");
@@ -1875,7 +1875,6 @@ namespace Slic3r {
                 }
                 else {
                     std::cout << "non-single instance !!!\n";
-                    int a = 0;
                 }
             }
 #endif // ENABLE_RELOAD_FROM_DISK_FOR_3MF
diff --git a/src/libslic3r/SupportMaterial.cpp b/src/libslic3r/SupportMaterial.cpp
index 1695075c8..33e74254e 100644
--- a/src/libslic3r/SupportMaterial.cpp
+++ b/src/libslic3r/SupportMaterial.cpp
@@ -1683,7 +1683,7 @@ size_t idx_higher_or_equal(IT begin, IT end, size_t idx, FN_HIGHER_EQUAL fn_high
               (fn_higher_equal(begin[idx_high]) ? idx_high : size);
     } else {
         // For the other layers of this batch of layers, search incrementally, which is cheaper than the binary search.
-        while (idx < size && ! fn_higher_equal(begin[idx]))
+        while (int(idx) < size && ! fn_higher_equal(begin[idx]))
             ++ idx;
     }
     return idx;
diff --git a/src/libslic3r/VoronoiOffset.cpp b/src/libslic3r/VoronoiOffset.cpp
index 7ad0f7af4..2108388f5 100644
--- a/src/libslic3r/VoronoiOffset.cpp
+++ b/src/libslic3r/VoronoiOffset.cpp
@@ -666,19 +666,21 @@ void annotate_inside_outside(VD &vd, const Lines &lines)
 
     // Set a VertexCategory, verify validity of the operation.
     auto annotate_vertex = [](const VD::vertex_type *vertex, VertexCategory new_vertex_category) {
+#ifndef NDEBUG
         VertexCategory vc = vertex_category(vertex);
         assert(vc == VertexCategory::Unknown || vc == new_vertex_category);
         assert(new_vertex_category == VertexCategory::Inside || 
                new_vertex_category == VertexCategory::Outside ||
                new_vertex_category == VertexCategory::OnContour);
+#endif // NDEBUG
         set_vertex_category(const_cast<VD::vertex_type*>(vertex), new_vertex_category);
     };
 
     // Set an EdgeCategory, verify validity of the operation.
     auto annotate_edge = [](const VD::edge_type *edge, EdgeCategory new_edge_category) {
+#ifndef NDEBUG
         EdgeCategory ec = edge_category(edge);
         assert(ec == EdgeCategory::Unknown || ec == new_edge_category);
-#ifndef NDEBUG
         switch (new_edge_category) {
         case EdgeCategory::PointsInside:
             assert(edge->vertex0() != nullptr);
@@ -693,7 +695,6 @@ void annotate_inside_outside(VD &vd, const Lines &lines)
         default:
             assert(false);
         }
-
 #endif // NDEBUG
         set_edge_category(const_cast<VD::edge_type*>(edge), new_edge_category);
     };
@@ -760,10 +761,12 @@ void annotate_inside_outside(VD &vd, const Lines &lines)
                 // Only one of the two vertices may lie on input contour.
                 const VD::vertex_type  *v0          = edge.vertex0();
                 const VD::vertex_type  *v1          = edge.vertex1();
+#ifndef NDEBUG
                 VertexCategory          v0_category = vertex_category(v0);
                 VertexCategory          v1_category = vertex_category(v1);
                 assert(v0_category != VertexCategory::OnContour || v1_category != VertexCategory::OnContour);
                 assert(! (on_contour(v0) && on_contour(v1)));
+#endif // NDEBUG
                 if (on_contour(v0))
                     annotate_vertex(v0, VertexCategory::OnContour);
                 else {
diff --git a/tests/libslic3r/test_voronoi.cpp b/tests/libslic3r/test_voronoi.cpp
index 189dde7ce..bbcea7301 100644
--- a/tests/libslic3r/test_voronoi.cpp
+++ b/tests/libslic3r/test_voronoi.cpp
@@ -176,13 +176,13 @@ TEST_CASE("Voronoi missing edges - Alessandro gapfill 12707", "[Voronoi]")
 
     std::mt19937 gen;
     std::uniform_int_distribution<coord_t> dist(-100, 100);
-    for (Point &p : poly.points) {
 #if 0
+    for (Point &p : poly.points) {
       // Wiggle the points a bit to find out whether this fixes the voronoi diagram for this particular polygon.
       p.x() = (p.x() += dist(gen));
       p.y() = (p.y() += dist(gen));
-#endif
     }
+#endif
 
     REQUIRE(intersecting_edges({ poly }).empty());
 
@@ -267,7 +267,7 @@ TEST_CASE("Voronoi weirdness", "[Voronoi]")
     };
 
 //    coord_t shift = 35058881;
-    coord_t shift_ok = 17000000;
+//    coord_t shift_ok = 17000000;
     coord_t shift = 35058881;
     Polygon poly {
         // <-4, 0>: bug