--- a/Wrapping/PythonCore/vtkPythonArgs.cxx.ORIG	2017-12-22 17:33:25.000000000 +0100
+++ b/Wrapping/PythonCore/vtkPythonArgs.cxx	2018-09-19 15:42:51.150239108 +0200
@@ -102,7 +102,7 @@
   else if (PyUnicode_Check(o))
   {
 #if PY_VERSION_HEX >= 0x03030000
-    a = PyUnicode_AsUTF8(o);
+    a = const_cast<T *>(PyUnicode_AsUTF8(o));
     return true;
 #else
     PyObject *s = _PyUnicode_AsDefaultEncodedString(o, nullptr);