diff --git a/scripts/Python/python-wrapper.swig b/scripts/Python/python-wrapper.swig
index a2c7a48..1acbe27 100644
--- a/scripts/Python/python-wrapper.swig
+++ b/scripts/Python/python-wrapper.swig
@@ -779,7 +779,7 @@
                 
             if (PyCallable_Check (pfunc))
             {
-                PyObject *argList = Py_BuildValue("S", SBProc_PyObj);
+                PyObject *argList = Py_BuildValue("(O)", SBProc_PyObj);
 
                 if (PyErr_Occurred ())
                 {