diff --git a/src/nagini_translation/translators/program.py b/src/nagini_translation/translators/program.py
index cb8e77be..e02dfbae 100644
--- a/src/nagini_translation/translators/program.py
+++ b/src/nagini_translation/translators/program.py
@@ -257,7 +257,7 @@ def create_inherit_check(self, method: PythonMethod, cls: PythonClass,
             pres = [not_null, new_type] + pres
 
         stmts, end_lbl = self.inline_method(method, args, method.result,
-                                            error_var, ctx)
+                                            optional_error_var, ctx)
 
         self._create_inherit_check_postamble(stmts, end_lbl, ctx)