diff --git a/src/ifcopenshell-python/ifcopenshell/api/geometry/add_representation.py b/src/ifcopenshell-python/ifcopenshell/api/geometry/add_representation.py
index 3d226a6787..f3a0fe6b85 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/geometry/add_representation.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/geometry/add_representation.py
@@ -369,7 +369,11 @@ class Usecase:
             else:
                 return self.create_curves_from_mesh(should_exclude_faces=should_exclude_faces, is_2d=is_2d)
         elif isinstance(self.settings["geometry"], bpy.types.Curve):
-            return self.create_curves_from_curve(is_2d=is_2d)
+            if self.file.schema == "IFC2X3":
+                return self.create_curves_from_curve_ifc2x3(is_2d=is_2d)
+            else:
+                return self.create_curves_from_curve(is_2d=is_2d)
+            
 
     def create_curves_from_mesh(self, should_exclude_faces=False, is_2d=False):
         curves = []
@@ -433,24 +437,32 @@ class Usecase:
             curves.append(self.file.createIfcPolyline(loop_points))
         return curves
 
-    def create_curves_from_curve(self, is_2d=False):
+    def create_curves_from_curve_ifc2x3(self, is_2d=False):
+        # TODO: support interpolated curves, not just polylines
+        dim = (lambda v: v.xy) if is_2d else (lambda v: v.xyz)
         results = []
         for spline in self.settings["geometry"].splines:
-            # TODO: support interpolated curves, not just polylines
-            points = []
-            for point in spline.bezier_points:
-                if is_2d:
-                    points.append(self.create_cartesian_point(point.co.x, point.co.y))
-                else:
-                    points.append(self.create_cartesian_point(point.co.x, point.co.y, point.co.z))
-            for point in spline.points:
-                if is_2d:
-                    points.append(self.create_cartesian_point(point.co.x, point.co.y))
-                else:
-                    points.append(self.create_cartesian_point(point.co.x, point.co.y, point.co.z))
+            points = spline.bezier_points[:] + spline.points[:]
             if spline.use_cyclic_u:
                 points.append(points[0])
-            results.append(self.file.createIfcPolyline(points))
+            ifc_points = [self.create_cartesian_point(*dim(point.co)) for point in points]
+            results.append(self.file.createIfcPolyline(ifc_points))
+        return results
+
+    def create_curves_from_curve(self, is_2d=False):
+        # TODO: support interpolated curves, not just polylines
+        dim = (lambda v: v.xy) if is_2d else (lambda v: v.xyz)
+        to_units = lambda v: Vector([self.convert_si_to_unit(i) for i in v])
+        builder = ifcopenshell.util.shape_builder.ShapeBuilder(self.file)
+        results = []
+
+        for spline in self.settings["geometry"].splines:
+            points = spline.bezier_points[:] + spline.points[:]
+
+            points = [to_units(dim(p.co)) for p in points]
+            closed_polyline = spline.use_cyclic_u and len(points) > 1
+            results.append(builder.polyline(points, closed=closed_polyline))
+
         return results
 
     def create_point_cloud_representation(self, is_2d=False):
diff --git a/src/ifcopenshell-python/ifcopenshell/util/shape_builder.py b/src/ifcopenshell-python/ifcopenshell/util/shape_builder.py
index 87d91e9274..27eb25a2e7 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/shape_builder.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/shape_builder.py
@@ -62,11 +62,22 @@ class ShapeBuilder:
             ifc_points = self.file.createIfcCartesianPointList3D(points)
 
         ifc_segments = []
-        for segment in segments:
+        # because IfcLineIndex support 2+ points
+        # we merge neighbor line segments into one
+        current_line_segment = []
+        last_segment = len(segments) - 1
+        for seg_i, segment in enumerate(segments):
             if len(segment) == 2:
-                ifc_segments.append(self.file.createIfcLineIndex(segment))
-            elif len(segment) == 3:
+                current_line_segment += segment
+
+            if current_line_segment and (len(segment) == 3 or seg_i == last_segment):
+                ifc_segments.append(self.file.createIfcLineIndex(current_line_segment))
+                current_line_segment = []
+
+            if len(segment) == 3:
                 ifc_segments.append(self.file.createIfcArcIndex(segment))
+
+        # NOTE: IfcIndexPolyCurve support only consequtive segments
         ifc_curve = self.file.createIfcIndexedPolyCurve(Points=ifc_points, Segments=ifc_segments)
         return ifc_curve