diff --git a/masque/shapes/poly_collection.py b/masque/shapes/poly_collection.py
index 73aca30..c714ed5 100644
--- a/masque/shapes/poly_collection.py
+++ b/masque/shapes/poly_collection.py
@@ -60,7 +60,7 @@ class PolyCollection(Shape):
             return
         for ii, ff in zip(
                 self._vertex_offsets,
-                chain(self._vertex_offsets, (self._vertex_lists.shape[0],)),
+                chain(self._vertex_offsets[1:], [self._vertex_lists.shape[0]]),
                 strict=True,
                 ):
             yield slice(ii, ff)