From 0927f2530065f91ebf951d1f44f5596fc14460c6 Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Wed, 18 Nov 2015 07:57:06 -0600
Subject: [PATCH] Fix bug in reimplementation of neighbor_lists.

---
 src/geometry.F90 | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/geometry.F90 b/src/geometry.F90
index 75165158bf..3f8b43d4cb 100644
--- a/src/geometry.F90
+++ b/src/geometry.F90
@@ -903,13 +903,17 @@ contains
     do i = 1, n_surfaces
       ! Copy positive neighbors to Surface instance
       j = neighbor_pos(i)%size()
-      allocate(surfaces(i)%obj%neighbor_pos(j))
-      surfaces(i)%obj%neighbor_pos(:) = neighbor_pos(i)%data(1:j)
+      if (j > 0) then
+        allocate(surfaces(i)%obj%neighbor_pos(j))
+        surfaces(i)%obj%neighbor_pos(:) = neighbor_pos(i)%data(1:j)
+      end if
 
       ! Copy negative neighbors to Surface instance
       j = neighbor_neg(i)%size()
-      allocate(surfaces(i)%obj%neighbor_neg(j))
-      surfaces(i)%obj%neighbor_neg(:) = neighbor_neg(i)%data(1:j)
+      if (j > 0) then
+        allocate(surfaces(i)%obj%neighbor_neg(j))
+        surfaces(i)%obj%neighbor_neg(:) = neighbor_neg(i)%data(1:j)
+      end if
     end do
 
   end subroutine neighbor_lists