diff --git a/src/ifcopenshell-python/ifcopenshell/api/boundary/assign_connection_geometry.py b/src/ifcopenshell-python/ifcopenshell/api/boundary/assign_connection_geometry.py
index 8237b6f1e1..9d988a4e82 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/boundary/assign_connection_geometry.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/boundary/assign_connection_geometry.py
@@ -127,7 +127,7 @@ class Usecase:
         return self.file.createIfcPlane(
             self.file.createIfcAxis2Placement3D(
                 self.create_point(location),
-                self.file.createIfcDirection(axis),
-                self.file.createIfcDirection(ref_direction),
+                self.file.createIfcDirection(ifc_safe_vector_type(axis)),
+                self.file.createIfcDirection(ifc_safe_vector_type(ref_direction)),
             )
         )