diff --git a/libsrc/csg/python_csg.cpp b/libsrc/csg/python_csg.cpp
index 30e7c23e..f6381b85 100644
--- a/libsrc/csg/python_csg.cpp
+++ b/libsrc/csg/python_csg.cpp
@@ -210,7 +210,7 @@ DLL_HEADER void ExportCSG()
            ([] (double x, double y) { return Vec<2>(x,y); }));
 
 
-#if BOOST_VERSION < 106000
+#if BOOST_VERSION >= 106000
   bp::register_ptr_to_python<shared_ptr<SPSolid>>();
 #endif
   bp::class_<SPSolid, shared_ptr<SPSolid>, boost::noncopyable> ("Solid", bp::no_init)
diff --git a/libsrc/meshing/python_mesh.cpp b/libsrc/meshing/python_mesh.cpp
index 6302f013..17d8f66e 100644
--- a/libsrc/meshing/python_mesh.cpp
+++ b/libsrc/meshing/python_mesh.cpp
@@ -296,7 +296,7 @@ DLL_HEADER void ExportNetgenMeshing()
   ;
   
   
-#if BOOST_VERSION < 106000
+#if BOOST_VERSION >= 106000
   bp::register_ptr_to_python<shared_ptr<Mesh>>();
 #endif
   bp::class_<Mesh,shared_ptr<Mesh>,boost::noncopyable>("Mesh", bp::no_init)