diff --git a/src/libslic3r/Print.cpp b/src/libslic3r/Print.cpp
index df50012b98..0a1bac4e4b 100644
--- a/src/libslic3r/Print.cpp
+++ b/src/libslic3r/Print.cpp
@@ -1095,8 +1095,10 @@ Print::ApplyStatus Print::apply(const Model &model, const DynamicPrintConfig &co
 			bool         fresh = print_object.region_volumes.empty();
             unsigned int volume_id = 0;
             for (const ModelVolume *volume : model_object.volumes) {
-                if (! volume->is_model_part() && ! volume->is_modifier())
-                    continue;
+                if (! volume->is_model_part() && ! volume->is_modifier()) {
+					++ volume_id;
+					continue;
+				}
                 int region_id = -1;
                 if (&print_object == &print_object0) {
                     // Get the config applied to this volume.
diff --git a/src/libslic3r/Print.hpp b/src/libslic3r/Print.hpp
index ad32f42baf..e5060cb766 100644
--- a/src/libslic3r/Print.hpp
+++ b/src/libslic3r/Print.hpp
@@ -107,7 +107,7 @@ public:
     // adds region_id, too, if necessary
     void add_region_volume(unsigned int region_id, int volume_id) {
         if (region_id >= region_volumes.size())
-			region_volumes.assign(region_id + 1, std::vector<int>());
+			region_volumes.resize(region_id + 1);
         region_volumes[region_id].emplace_back(volume_id);
     }
     // This is the *total* layer count (including support layers)