diff --git a/pointpats/geometry.py b/pointpats/geometry.py
index a21de4b..ff0a2a5 100644
--- a/pointpats/geometry.py
+++ b/pointpats/geometry.py
@@ -125,7 +125,7 @@ def _(shape: spatial.Delaunay, x: float, y: float):
     If the returned simplex index is -1, then the point is not
     within a simplex of the triangulation. 
     """
-    return shape.find_simplex((x, y)) > 0
+    return shape.find_simplex((x, y)) >= 0
 
 
 @contains.register
diff --git a/pointpats/ripley.py b/pointpats/ripley.py
index d89ef5a..add25c8 100644
--- a/pointpats/ripley.py
+++ b/pointpats/ripley.py
@@ -126,7 +126,7 @@ def _(shape: spatial.Delaunay, x: float, y: float):
     If the returned simplex index is -1, then the point is not
     within a simplex of the triangulation. 
     """
-    return shape.find_simplex((x, y)) > 0
+    return shape.find_simplex((x, y)) >= 0
 
 
 @_contains.register