diff --git a/masque/utils/vertices.py b/masque/utils/vertices.py
index 7d3791c..c4a7cb6 100644
--- a/masque/utils/vertices.py
+++ b/masque/utils/vertices.py
@@ -62,7 +62,7 @@ def poly_contains_points(
         vertices: ArrayLike,
         points: ArrayLike,
         include_boundary: bool = True,
-        ) -> NDArray[numpy.int_]:
+        ) -> NDArray[numpy.bool_]:
     """
     Tests whether the provided points are inside the implicitly closed polygon
     described by the provided list of vertices.
@@ -81,7 +81,7 @@ def poly_contains_points(
     vertices = numpy.asarray(vertices, dtype=float)
 
     if points.size == 0:
-        return numpy.zeros(0, dtype=numpy.int8)
+        return numpy.zeros(0, dtype=bool)
 
     min_bounds = numpy.min(vertices, axis=0)[None, :]
     max_bounds = numpy.max(vertices, axis=0)[None, :]