diff --git a/share/lib/python/neuron/rxd/region.py b/share/lib/python/neuron/rxd/region.py
index a044dc146e..7ed4a55049 100644
--- a/share/lib/python/neuron/rxd/region.py
+++ b/share/lib/python/neuron/rxd/region.py
@@ -344,10 +344,10 @@ def __repr__(self):
     def _short_repr(self):
         return "Extracellular"
 
-    def volume(self, species):
+    def _volume(self, species):
         return sum(species.nodes(self).volume)
 
-    def _volume(self, index):
+    def volume(self, index):
         """Returns the volume of the voxel at a given index"""
         if numpy.isscalar(self.alpha):
             return numpy.prod(self._dx) * self.alpha