diff --git a/mpython/runtime.py b/mpython/runtime.py
index f2e30ef..302bc81 100644
--- a/mpython/runtime.py
+++ b/mpython/runtime.py
@@ -33,7 +33,7 @@ def _process_argin(*args, **kwargs):
 
     @staticmethod
     def _process_argout(res):
-        return MatlabType.from_any(res)
+        return MatlabType._from_runtime(res)
 
     @staticmethod
     def _import_initialize():