diff --git a/src/libslic3r/Format/3mf.cpp b/src/libslic3r/Format/3mf.cpp
index 131278e9f1..eca057a5be 100644
--- a/src/libslic3r/Format/3mf.cpp
+++ b/src/libslic3r/Format/3mf.cpp
@@ -1922,7 +1922,7 @@ namespace Slic3r {
             {
                 int min_id = its.indices.front()[0];
                 int max_id = min_id;
-                for (const Vec3i face : its.indices) {
+                for (const Vec3i& face : its.indices) {
                     for (const int tri_id : face) {
                         if (tri_id < 0 || tri_id >= int(geometry.vertices.size())) {
                             add_error("Found invalid vertex id");
diff --git a/src/libslic3r/Format/AMF.cpp b/src/libslic3r/Format/AMF.cpp
index 48c25fc4d7..bcc5c8b4a2 100644
--- a/src/libslic3r/Format/AMF.cpp
+++ b/src/libslic3r/Format/AMF.cpp
@@ -626,7 +626,7 @@ void AMFParserContext::endElement(const char * /* name */)
             // Verify validity of face indices, find the vertex span.
             int min_id = m_volume_facets.front()[0];
             int max_id = min_id;
-            for (const Vec3i face : m_volume_facets) {
+            for (const Vec3i& face : m_volume_facets) {
                 for (const int tri_id : face) {
                     if (tri_id < 0 || tri_id >= int(m_object_vertices.size())) {
                         this->stop("Malformed triangle mesh");
diff --git a/src/libslic3r/GCode/GCodeProcessor.cpp b/src/libslic3r/GCode/GCodeProcessor.cpp
index 2397a17ff7..3e42c91f5b 100644
--- a/src/libslic3r/GCode/GCodeProcessor.cpp
+++ b/src/libslic3r/GCode/GCodeProcessor.cpp
@@ -1456,7 +1456,7 @@ void GCodeProcessor::apply_config_simplify3d(const std::string& filename)
         
         begin = skip_whitespaces(begin, end);
         end   = remove_eols(begin, end);
-        if (begin != end)
+        if (begin != end) {
             if (*begin == ';') {
                 // Comment.
                 begin = skip_whitespaces(++ begin, end);
@@ -1485,6 +1485,7 @@ void GCodeProcessor::apply_config_simplify3d(const std::string& filename)
                 // Some non-empty G-code line detected, stop parsing config comments.
                 reader.quit_parsing();
             }
+        }
     });
 
     if (m_result.extruders_count == 0)
diff --git a/src/libslic3r/PrintApply.cpp b/src/libslic3r/PrintApply.cpp
index da26f905cb..0f70cf3cc1 100644
--- a/src/libslic3r/PrintApply.cpp
+++ b/src/libslic3r/PrintApply.cpp
@@ -1300,7 +1300,7 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
                     num_extruders,
                     painting_extruders,
                     *print_object_regions,
-                    [&print_object, it_print_object, it_print_object_end, &update_apply_status](const PrintRegionConfig &old_config, const PrintRegionConfig &new_config, const t_config_option_keys &diff_keys) {
+                    [it_print_object, it_print_object_end, &update_apply_status](const PrintRegionConfig &old_config, const PrintRegionConfig &new_config, const t_config_option_keys &diff_keys) {
                         for (auto it = it_print_object; it != it_print_object_end; ++it)
                             if ((*it)->m_shared_regions != nullptr)
                                 update_apply_status((*it)->invalidate_state_by_config_options(old_config, new_config, diff_keys));
diff --git a/src/libslic3r/TriangleMesh.cpp b/src/libslic3r/TriangleMesh.cpp
index f5fea32f82..7285fc8fa2 100644
--- a/src/libslic3r/TriangleMesh.cpp
+++ b/src/libslic3r/TriangleMesh.cpp
@@ -465,7 +465,7 @@ TriangleMesh TriangleMesh::convex_hull_3d() const
     std::vector<int>    map_dst_vertices;
 #ifndef NDEBUG
     Vec3f               centroid = Vec3f::Zero();
-    for (auto pt : this->its.vertices)
+    for (const stl_vertex& pt : this->its.vertices)
         centroid += pt;
     centroid /= float(this->its.vertices.size());
 #endif // NDEBUG
@@ -1261,7 +1261,7 @@ bool its_write_stl_ascii(const char *file, const char *label, const std::vector<
 
     fprintf(fp, "solid  %s\n", label);
 
-    for (const stl_triangle_vertex_indices face : indices) {
+    for (const stl_triangle_vertex_indices& face : indices) {
         Vec3f vertex[3] = { vertices[face(0)], vertices[face(1)], vertices[face(2)] };
         Vec3f normal    = (vertex[1] - vertex[0]).cross(vertex[2] - vertex[1]).normalized();
         fprintf(fp, "  facet normal % .8E % .8E % .8E\n", normal(0), normal(1), normal(2));
@@ -1301,7 +1301,7 @@ bool its_write_stl_binary(const char *file, const char *label, const std::vector
     stl_facet f;
     f.extra[0] = 0;
     f.extra[1] = 0;
-    for (const stl_triangle_vertex_indices face : indices) {
+    for (const stl_triangle_vertex_indices& face : indices) {
         f.vertex[0] = vertices[face(0)];
         f.vertex[1] = vertices[face(1)];
         f.vertex[2] = vertices[face(2)];