diff --git a/surf/geometry.py b/surf/geometry.py
index 90de39f..a43a40e 100644
--- a/surf/geometry.py
+++ b/surf/geometry.py
@@ -162,8 +162,7 @@ class PolygonMesh(object):
         """
         if self._faces_for_edge is None:
             # TODO: eventually support generating this ourselves ...
-            raise AttributeError("Not yet implemented if you don't explicitly"
-            " pass this in")
+            raise NotImplementedError
         return self._faces_for_edge
 
     @property
@@ -171,8 +170,7 @@ class PolygonMesh(object):
         """returns a list of edge indices for a given face index."""
         if self._edges_for_face is None:
             # TODO: eventually support generating this ourselves ...
-            raise AttributeError("Not yet implemented if you don't explicitly"
-            " pass this in")
+            raise NotImplementedError
         return self._edges_for_face
 
     @property
@@ -180,8 +178,7 @@ class PolygonMesh(object):
         """returns a list of edge indices for a given vertex index."""
         if self._edges_for_vert is None:
             # TODO: eventually support generating this ourselves ...
-            raise AttributeError("Not yet implemented if you don't explicitly"
-            " pass this in")
+            raise NotImplementedError
         return self._edges_for_vert
 
     @property
@@ -189,8 +186,7 @@ class PolygonMesh(object):
         """returns a list of face indices for a given vert index."""
         if self._faces_for_vert is None:
             # TODO: eventually support generating this ourselves ...
-            raise AttributeError("Not yet implemented if you don't explicitly"
-            " pass this in")
+            raise NotImplementedError
         return self._faces_for_vert
 
     def __unicode__(self):