Index: urdf/urdfdom_compatibility.h.in
===================================================================
--- urdf.orig/urdfdom_compatibility.h.in
+++ urdf/urdfdom_compatibility.h.in
@@ -85,10 +85,12 @@ URDF_TYPEDEF_CLASS_POINTER(Model);
 #include <urdf_world/types.h>
 
 namespace urdf {
+class ModelInterface;
 typedef std::shared_ptr<ModelInterface> ModelInterfaceSharedPtr;
 typedef std::shared_ptr<const ModelInterface> ModelInterfaceConstSharedPtr;
 typedef std::weak_ptr<ModelInterface> ModelInterfaceWeakPtr;
 
+class Model;
 typedef std::shared_ptr<Model> ModelSharedPtr;
 typedef std::shared_ptr<const Model> ModelConstSharedPtr;
 typedef std::weak_ptr<Model> ModelWeakPtr;