diff --git a/Cantera/python/Cantera/ThermoPhase.py b/Cantera/python/Cantera/ThermoPhase.py
index 718d9f99d..b4e37df4e 100644
--- a/Cantera/python/Cantera/ThermoPhase.py
+++ b/Cantera/python/Cantera/ThermoPhase.py
@@ -2,6 +2,7 @@
 thermodynamic phases.  """
 
 from Cantera.Phase import Phase
+from Numeric import zeros
 
 import _cantera
 import types