diff --git a/Code/GamePhysics/PhysicsAPI.h b/Code/GamePhysics/PhysicsAPI.h
index 3e213dc4..4e1844f5 100644
--- a/Code/GamePhysics/PhysicsAPI.h
+++ b/Code/GamePhysics/PhysicsAPI.h
@@ -238,6 +238,7 @@ namespace Oyster
 			};
 
 			typedef SubscriptMessage (*EventAction_Collision)( const ICustomBody *proto, const ICustomBody *deuter );
+			typedef void (*EventAction_CollisionResponse)( const ICustomBody *proto, const ICustomBody *deuter, ::Oyster::Math::Float kineticEnergyLoss );
 			typedef void (*EventAction_Move)( const ICustomBody *object );
 			typedef Struct::SimpleBodyDescription SimpleBodyDescription;
 			typedef Struct::SphericalBodyDescription SphericalBodyDescription;