diff --git a/src/libslic3r/GCode.cpp b/src/libslic3r/GCode.cpp
index aac9ba79f..18052e425 100644
--- a/src/libslic3r/GCode.cpp
+++ b/src/libslic3r/GCode.cpp
@@ -2619,7 +2619,7 @@ void GCode::process_layers(
                 for (size_t layer_idx = range.begin(); layer_idx < range.end(); ++layer_idx) {
                     print.throw_if_canceled();
                     if (layer_idx > 0) {
-                        LayerToPrint &layer = layers_to_print[layer_idx++];
+                        LayerToPrint &layer = layers_to_print[layer_idx];
                         cooling_buffer.apply_smooth_speed(smooth_calculator, layers_extruder_adjustments[layer_idx], layer_idx);
                     }
                 }
diff --git a/src/libslic3r/PrintObject.cpp b/src/libslic3r/PrintObject.cpp
index 65c9405a5..df4ce0666 100644
--- a/src/libslic3r/PrintObject.cpp
+++ b/src/libslic3r/PrintObject.cpp
@@ -170,6 +170,10 @@ void PrintObject::merge_layer_node(const size_t layer_id, int &max_merged_id, st
                 continue;
 
             auto it = node_record.find(appear_id[appear_node_idx]);
+            //protect
+            if (it == node_record.end())
+                continue;
+
             std::vector<std::pair<int, int>> &appear_node_pos = it->second;
 
             for (size_t node_idx = 0; node_idx < appear_node_pos.size(); ++node_idx) {