diff --git a/src/slic3r/GUI/GUI_ObjectManipulation.cpp b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
index bbae228e06..d7bf147877 100644
--- a/src/slic3r/GUI/GUI_ObjectManipulation.cpp
+++ b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
@@ -951,7 +951,7 @@ void ObjectManipulation::update_reset_buttons_visibility()
 
         show_drop_to_bed = std::abs(min_z) > EPSILON;
         const GLVolume* volume = selection.get_first_volume();
-        Geometry::Transformation trafo = selection.is_single_full_instance() ? volume->get_instance_transformation() : volume->get_volume_transformation();
+        const Geometry::Transformation trafo = selection.is_single_full_instance() ? volume->get_instance_transformation() : volume->get_volume_transformation();
 
         const Geometry::TransformationSVD trafo_svd(trafo);
         show_rotation = trafo_svd.rotation;
diff --git a/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp b/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
index 88803e59d4..947ef2df8e 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
@@ -3,7 +3,7 @@
 #include "slic3r/GUI/GLCanvas3D.hpp"
 #include "slic3r/GUI/GUI_App.hpp"
 #include "slic3r/GUI/Plater.hpp"
-
+#include "slic3r/GUI/GUI_ObjectManipulation.hpp"
 #include "slic3r/GUI/Gizmos/GLGizmosCommon.hpp"
 
 #include "libslic3r/Geometry/ConvexHull.hpp"
@@ -38,6 +38,7 @@ bool GLGizmoFlatten::on_mouse(const wxMouseEvent &mouse_event)
                 // Rotate the object so the normal points downward:
                 selection.flattening_rotate(m_planes[m_hover_id].normal);
                 m_parent.do_rotate(L("Gizmo-Place on Face"));
+                wxGetApp().obj_manipul()->set_dirty();
             }
             return true;
         }