diff --git a/snarled/clipper.py b/snarled/clipper.py
index f6ba60a..8c01e2e 100644
--- a/snarled/clipper.py
+++ b/snarled/clipper.py
@@ -6,7 +6,7 @@ from typing import Sequence, Optional, List
 from numpy.typing import ArrayLike
 from pyclipper import (
     Pyclipper, PT_CLIP, PT_SUBJECT, CT_UNION, CT_INTERSECTION, PFT_NONZERO, PFT_EVENODD,
-    PyPolyNode,
+    PyPolyNode, CT_DIFFERENCE,
     )
 
 from .types import contour_t