diff -r 5a66d4be2e49 -r b57a38ce3f34 py_ext/PythonFileCTNMixin.py
--- a/py_ext/PythonFileCTNMixin.py	Wed May 17 23:36:12 2023 +0200
+++ b/py_ext/PythonFileCTNMixin.py	Wed May 17 23:59:45 2023 +0200
@@ -243,7 +243,7 @@
         # write generated content to python file
         runtimefile_path = os.path.join(buildpath,
                                         "runtime_%s.py" % location_str)
-        runtimefile = open(runtimefile_path, 'w')
+        runtimefile = open(runtimefile_path, 'wb')
         runtimefile.write(PyFileContent.encode('utf-8'))
         runtimefile.close()