diff --git a/src/ifcopenshell-python/ifcopenshell/util/shape_builder.py b/src/ifcopenshell-python/ifcopenshell/util/shape_builder.py
index 31750774cc..26f5146319 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/shape_builder.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/shape_builder.py
@@ -1146,7 +1146,7 @@ class ShapeBuilder:
         if polyline.is_a("IfcIndexedPolyCurve"):
             coords = np.array(polyline.Points.CoordList)
         elif polyline.is_a("IfcPolyline"):
-            coords = np.array(p.Coordinates for p in polyline.Points)
+            coords = np.array(tuple(p.Coordinates for p in polyline.Points))
         else:
             raise Exception(f"Unsupported polyline type: {polyline.is_a()}")
         return coords