diff --git a/openstudiocore/src/model/ModelSimulation.i b/openstudiocore/src/model/ModelSimulation.i
index 3cb48c7977f..adf0af26dba 100644
--- a/openstudiocore/src/model/ModelSimulation.i
+++ b/openstudiocore/src/model/ModelSimulation.i
@@ -30,7 +30,7 @@
 
 UNIQUEMODELOBJECT_TEMPLATES(SimulationControl);
 UNIQUEMODELOBJECT_TEMPLATES(LightingSimulationControl);
-MODELOBJECT_TEMPLATES(SizingParameters);
+UNIQUEMODELOBJECT_TEMPLATES(SizingParameters);
 MODELOBJECT_TEMPLATES(SizingPeriod);
 UNIQUEMODELOBJECT_TEMPLATES(TimeDependentValuation);
 UNIQUEMODELOBJECT_TEMPLATES(WeatherFile);
@@ -60,7 +60,7 @@ UNIQUEMODELOBJECT_TEMPLATES(YearDescription);
 
 SWIG_UNIQUEMODELOBJECT(SimulationControl);
 SWIG_UNIQUEMODELOBJECT(LightingSimulationControl);
-SWIG_MODELOBJECT(SizingParameters, 1);
+SWIG_UNIQUEMODELOBJECT(SizingParameters);
 SWIG_MODELOBJECT(SizingPeriod, 0);
 SWIG_UNIQUEMODELOBJECT(TimeDependentValuation);
 SWIG_UNIQUEMODELOBJECT(WeatherFile);