diff --git a/xs/src/libslic3r/Format/3mf.cpp b/xs/src/libslic3r/Format/3mf.cpp
index b838f65c1..4dc40bd3c 100644
--- a/xs/src/libslic3r/Format/3mf.cpp
+++ b/xs/src/libslic3r/Format/3mf.cpp
@@ -1738,10 +1738,7 @@ namespace Slic3r {
                 stream << "   </" << COMPONENTS_TAG << ">\n";
             }
 
-            Transform3d t = Transform3d::Identity();
-            t.translate(Vec3d(instance->offset(0), instance->offset(1), 0.0));
-            t.rotate(Eigen::AngleAxisd(instance->rotation, Vec3d::UnitZ()));
-            t.scale(instance->scaling_factor);
+            Transform3d t = instance->world_matrix();
             build_items.emplace_back(instance_id, t);
 
             stream << "  </" << OBJECT_TAG << ">\n";
diff --git a/xs/src/slic3r/GUI/GLCanvas3D.cpp b/xs/src/slic3r/GUI/GLCanvas3D.cpp
index 73966a7f5..36f664f34 100644
--- a/xs/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/xs/src/slic3r/GUI/GLCanvas3D.cpp
@@ -2999,9 +2999,9 @@ void GLCanvas3D::on_mouse(wxMouseEvent& evt)
             if (m_gizmos.get_current_type() == Gizmos::Flatten) {
                 // Rotate the object so the normal points downward:
                 Vec3d normal = m_gizmos.get_flattening_normal();
-                if (normal != Vec3d::Zero()) {
-                    Vec3d axis = normal(2) > 0.999f ? Vec3d::UnitX() : normal.cross(-Vec3d::UnitZ());
-                    float angle = acos(-normal(2));
+                if (normal(0) != 0.0 || normal(1) != 0.0 || normal(2) != 0.0) {
+                    Vec3d axis = normal(2) > 0.999 ? Vec3d::UnitX() : normal.cross(-Vec3d::UnitZ()).normalized();
+                    float angle = acos(clamp(-1.0, 1.0, -normal(2)));
                     m_on_gizmo_rotate_callback.call(angle, (float)axis(0), (float)axis(1), (float)axis(2));
                 }
             }
diff --git a/xs/src/slic3r/GUI/GLGizmo.cpp b/xs/src/slic3r/GUI/GLGizmo.cpp
index a35165db4..aa4152c85 100644
--- a/xs/src/slic3r/GUI/GLGizmo.cpp
+++ b/xs/src/slic3r/GUI/GLGizmo.cpp
@@ -1282,7 +1282,7 @@ bool GLGizmoFlatten::is_plane_update_necessary() const
 Vec3d GLGizmoFlatten::get_flattening_normal() const {
     Vec3d normal = m_model_object->instances.front()->world_matrix().matrix().block(0, 0, 3, 3) * m_normal;
     m_normal = Vec3d::Zero();
-    return normal;
+    return normal.normalized();
 }
 
 } // namespace GUI