diff --git a/openmc/material.py b/openmc/material.py
index c89109bfa6..54ff0b5129 100644
--- a/openmc/material.py
+++ b/openmc/material.py
@@ -928,9 +928,9 @@ class Material(IDManagerMixin):
 
         if units == 'Bq':
             multiplier = self.volume
-        elif units == 'Bq/g':
-            multiplier = 1
         elif units == 'Bq/cm3':
+            multiplier = 1
+        elif units == 'Bq/g':
             multiplier = 1.0 / self.get_mass_density()
 
         activity = {}