gistfile1.diff

diff --git a/python/firedrake/core_types.pyx b/python/firedrake/core_types.pyx
index 3a97056..b6427f7 100644
--- a/python/firedrake/core_types.pyx
+++ b/python/firedrake/core_types.pyx
@@ -830,9 +830,12 @@ class FunctionSpaceBase(object):
             else:
                 self.interior_facet_node_list = None
 
-            self.exterior_facet_node_list = \
-                np.array(<int[:mesh.exterior_facets.count,:element_f.ndof]>
-                         function_space.exterior_facet_node_list)
+            if mesh.exterior_facets.count > 0:
+                self.exterior_facet_node_list = \
+                    np.array(<int[:mesh.exterior_facets.count,:element_f.ndof]>
+                             function_space.exterior_facet_node_list)
+            else:
+                self.exterior_facet_node_list = None
 
         # Note: this is the function space rank. The value rank may be different.
         self.rank = rank