diff --git a/src/libslic3r/Model.cpp b/src/libslic3r/Model.cpp
index 20c4a44b2..900397f70 100644
--- a/src/libslic3r/Model.cpp
+++ b/src/libslic3r/Model.cpp
@@ -719,12 +719,13 @@ ModelInstance* ModelObject::add_instance(const ModelInstance &other)
     return i;
 }
 
-ModelInstance* ModelObject::add_instance(const Vec3d &offset, const Vec3d &scaling_factor, const Vec3d &rotation)
+ModelInstance* ModelObject::add_instance(const Vec3d &offset, const Vec3d &scaling_factor, const Vec3d &rotation, const Vec3d &mirror)
 {
     auto *instance = add_instance();
     instance->set_offset(offset);
     instance->set_scaling_factor(scaling_factor);
     instance->set_rotation(rotation);
+    instance->set_mirror(mirror);
     return instance;
 }
 
diff --git a/src/libslic3r/Model.hpp b/src/libslic3r/Model.hpp
index e65228d80..947301437 100644
--- a/src/libslic3r/Model.hpp
+++ b/src/libslic3r/Model.hpp
@@ -200,7 +200,7 @@ public:
 
     ModelInstance*          add_instance();
     ModelInstance*          add_instance(const ModelInstance &instance);
-    ModelInstance*          add_instance(const Vec3d &offset, const Vec3d &scaling_factor, const Vec3d &rotation);
+    ModelInstance*          add_instance(const Vec3d &offset, const Vec3d &scaling_factor, const Vec3d &rotation, const Vec3d &mirror);
     void                    delete_instance(size_t idx);
     void                    delete_last_instance();
     void                    clear_instances();
diff --git a/src/slic3r/GUI/Plater.cpp b/src/slic3r/GUI/Plater.cpp
index a1ca93d62..941a181d3 100644
--- a/src/slic3r/GUI/Plater.cpp
+++ b/src/slic3r/GUI/Plater.cpp
@@ -2628,7 +2628,7 @@ void Plater::increase_instances(size_t num)
     float offset = 10.0;
     for (size_t i = 0; i < num; i++, offset += 10.0) {
         Vec3d offset_vec = model_instance->get_offset() + Vec3d(offset, offset, 0.0);
-        model_object->add_instance(offset_vec, model_instance->get_scaling_factor(), model_instance->get_rotation());
+        model_object->add_instance(offset_vec, model_instance->get_scaling_factor(), model_instance->get_rotation(), model_instance->get_mirror());
 //        p->print.get_object(obj_idx)->add_copy(Slic3r::to_2d(offset_vec));
     }