diff --git a/src/libslic3r/Layer.cpp b/src/libslic3r/Layer.cpp
index ddc16cddf..c42bde7d0 100644
--- a/src/libslic3r/Layer.cpp
+++ b/src/libslic3r/Layer.cpp
@@ -206,6 +206,10 @@ void Layer::make_perimeters()
                         slices[surface.extra_perimeters].emplace_back(surface);
                     if (layerm->region()->config().fill_density > layerm_config->region()->config().fill_density)
                     	layerm_config = layerm;
+                    //clean list as only the layerm_config will have these ones recomputed
+                    layerm->perimeters.clear();
+                    layerm->thin_fills.clear();
+                    layerm->fill_no_overlap_expolygons.clear();
                 }
                 // merge the surfaces assigned to each group
                 for (std::pair<const unsigned short,Surfaces> &surfaces_with_extra_perimeters : slices)
diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index d61c8abeb..c6b0b55fa 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -5239,7 +5239,8 @@ void PrintConfigDef::handle_legacy(t_config_option_key &opt_key, std::string &va
     } else if (opt_key == "z_steps_per_mm") {
         opt_key = "z_step";
         float v = boost::lexical_cast<float>(value);
-        value = boost::lexical_cast<std::string>(1/v);
+        if(v > 0)
+            value = boost::lexical_cast<std::string>(1/v);
     } else if (opt_key == "infill_not_connected") {
         opt_key = "infill_connection";
         if (value == "1")
diff --git a/src/slic3r/GUI/GUI_ObjectList.cpp b/src/slic3r/GUI/GUI_ObjectList.cpp
index f9fef6521..dbc332303 100644
--- a/src/slic3r/GUI/GUI_ObjectList.cpp
+++ b/src/slic3r/GUI/GUI_ObjectList.cpp
@@ -786,6 +786,11 @@ void ObjectList::copy_settings_to_clipboard()
 void ObjectList::paste_settings_into_list()
 {
     wxDataViewItem item = GetSelection();
+    if (!item.IsOk()) {
+        BOOST_LOG_TRIVIAL(error) << "Warning: can't paste settings on empty selection\n";
+        return;
+    }
+
     assert(item.IsOk());
     if (m_objects_model->GetItemType(item) & itSettings)
         item = m_objects_model->GetParent(item);