diff --git a/python/sdist/amici/numpy.py b/python/sdist/amici/numpy.py
index 487e5d7b98..8a1c687388 100644
--- a/python/sdist/amici/numpy.py
+++ b/python/sdist/amici/numpy.py
@@ -95,7 +95,7 @@ def __init__(self, swigptr):
         for field in self._field_names:
             if field not in dir(self):
                 setattr(
-                    self,
+                    self.__class__,
                     field,
                     property(lambda self_: self_.__getitem__(field)),
                 )