diff --git a/src/ifcopenshell-python/ifcopenshell/geom/occ_utils.py b/src/ifcopenshell-python/ifcopenshell/geom/occ_utils.py
index 2d5be63210..3f2446fddd 100644
--- a/src/ifcopenshell-python/ifcopenshell/geom/occ_utils.py
+++ b/src/ifcopenshell-python/ifcopenshell/geom/occ_utils.py
@@ -216,6 +216,11 @@ def get_bounding_box_center(bbox):
 
 def serialize_shape(shape):
     shapes = BRepTools.BRepTools_ShapeSet()
+
+    # @todo provide method to get ifcopenshell's built-in occt version to
+    # see whether this is necessary
+    shapes.SetFormatNb(2)
+
     shapes.Add(shape)
     return shapes.WriteToString()