diff --git a/lib/stitches/tangential_fill_stitch_line_creator.py b/lib/stitches/tangential_fill_stitch_line_creator.py
index e0bf62e6b..466fd6b69 100644
--- a/lib/stitches/tangential_fill_stitch_line_creator.py
+++ b/lib/stitches/tangential_fill_stitch_line_creator.py
@@ -288,7 +288,7 @@ def offset_poly(poly, offset, join_style, stitch_distance, min_stitch_distance,
                     result = Polygon(outer).difference(
                         MultiPolygon(poly_inners))
                 else:
-                    result = MultiPolygon(outer).difference(
+                    result = MultiPolygon(polygonize(outer)).difference(
                         MultiPolygon(poly_inners))
 
             if not result.is_empty and result.area > offset * offset / 10: