diff --git a/cell.cpp b/cell.cpp
index cbb055d8..2eaca81f 100644
--- a/cell.cpp
+++ b/cell.cpp
@@ -1423,6 +1423,7 @@ EX int valence() {
 
 /** portalspaces are not defined outside of a boundary */
 EX bool is_boundary(cell *c) {
+  if(c == &out_of_bounds) return true;
   return (cgflags & qPORTALSPACE) && isWall(c->wall);
   }