diff --git a/src/libslic3r/ExtrusionEntityCollection.cpp b/src/libslic3r/ExtrusionEntityCollection.cpp
index d1d6f91dab1..9008360ebf3 100644
--- a/src/libslic3r/ExtrusionEntityCollection.cpp
+++ b/src/libslic3r/ExtrusionEntityCollection.cpp
@@ -86,13 +86,13 @@ void ExtrusionEntityCollection::chained_path_from(const Point &start_near)
     if (this->m_no_sort) {
         if (this->m_can_reverse) {
             if (m_entities.size() > 1) {
-                //can't sort myself, ask first and last thign to sort itself so the first point of each are the best ones
+                //can't sort myself, ask first and last thing to sort itself so the first point of each are the best ones
                 if (m_entities.front()->is_collection()) {
                     assert(dynamic_cast<ExtrusionEntityCollection*>(m_entities.front()) != nullptr);
                     static_cast<ExtrusionEntityCollection*>(m_entities.front())->chained_path_from(start_near);
                 } else if (m_entities.front()->can_reverse() &&
                            m_entities.front()->first_point().distance_to_square(start_near) >
-                               m_entities.front()->first_point().distance_to_square(start_near)) {
+                               m_entities.front()->last_point().distance_to_square(start_near)) {
                     m_entities.front()->reverse();
                 }
                 if (m_entities.back()->is_collection()) {
@@ -100,7 +100,7 @@ void ExtrusionEntityCollection::chained_path_from(const Point &start_near)
                     static_cast<ExtrusionEntityCollection*>(m_entities.back())->chained_path_from(start_near);
                 } else if (m_entities.back()->can_reverse() &&
                            m_entities.back()->first_point().distance_to_square(start_near) >
-                               m_entities.back()->first_point().distance_to_square(start_near)) {
+                               m_entities.back()->last_point().distance_to_square(start_near)) {
                     m_entities.back()->reverse();
                 }
                 //now check if it's better for us to reverse
@@ -110,14 +110,14 @@ void ExtrusionEntityCollection::chained_path_from(const Point &start_near)
                     this->reverse();
                 }
             }
-            // now we are in our good order, update the internals
+            // now we are in our good order, update the internals to the final order
             Point last_point = start_near;
             for (ExtrusionEntity *entity : m_entities) {
                 if (entity->is_collection()) {
                     assert(dynamic_cast<ExtrusionEntityCollection*>(entity) != nullptr);
                     static_cast<ExtrusionEntityCollection*>(entity)->chained_path_from(last_point);
                 } else if (entity->can_reverse() && entity->first_point().distance_to_square(last_point) >
-                                                        entity->first_point().distance_to_square(last_point)) {
+                                                        entity->last_point().distance_to_square(last_point)) {
                     entity->reverse();
                 }
                 last_point = entity->last_point();
diff --git a/src/libslic3r/GCode.cpp b/src/libslic3r/GCode.cpp
index 2db5d549790..84f8697b534 100644
--- a/src/libslic3r/GCode.cpp
+++ b/src/libslic3r/GCode.cpp
@@ -5718,7 +5718,7 @@ void GCode::_extrude_line_cut_corner(std::string& gcode_str, const Line& line, c
 
 double GCode::compute_e_per_mm(double path_mm3_per_mm) {
     // no e if no extrusion axis
-    if (m_writer.extrusion_axis().empty())
+    if (m_writer.extrusion_axis().empty() || path_mm3_per_mm <= 0)
         return 0;
     // compute
     double e_per_mm = path_mm3_per_mm
diff --git a/src/slic3r/GUI/DoubleSlider.cpp b/src/slic3r/GUI/DoubleSlider.cpp
index 4182f5a09cd..1e588fcf63c 100644
--- a/src/slic3r/GUI/DoubleSlider.cpp
+++ b/src/slic3r/GUI/DoubleSlider.cpp
@@ -467,8 +467,8 @@ bool Control::ensure_correctly_filled() const
         //m_layers_areas.clear();
     }
     if (!m_layers_values.empty()) {
-        ok = m_is_wipe_tower;
-        assert(m_is_wipe_tower);
+        //ok = m_is_wipe_tower;
+        //assert(m_is_wipe_tower);
         //m_is_wipe_tower = false;
     }