diff --git a/python/sdist/amici/swig.py b/python/sdist/amici/swig.py
index ef75646389..ea7ad1f3a1 100644
--- a/python/sdist/amici/swig.py
+++ b/python/sdist/amici/swig.py
@@ -97,9 +97,9 @@ def _new_annot(self, old_annot: str):
         ) in self.mapping:
             value_type_annot = self.mapping[value_type]
             if isinstance(value_type_annot, ast.Constant):
-                return ast.Name(f"Tuple['{value_type_annot.value}']")
+                return ast.Name(f"tuple['{value_type_annot.value}']")
             if isinstance(value_type_annot, ast.Name):
-                return ast.Name(f"Tuple[{value_type_annot.id}]")
+                return ast.Name(f"tuple[{value_type_annot.id}]")
 
         return ast.Constant(old_annot)