diff --git a/source/mijin/container/optional.hpp b/source/mijin/container/optional.hpp
index c3bd31d..ecdb91b 100644
--- a/source/mijin/container/optional.hpp
+++ b/source/mijin/container/optional.hpp
@@ -198,7 +198,7 @@ private:
                 {
                     std::invoke(std::forward<TErrorCallable>(onError));
                 }
-                return NULL_OPTIONAL;
+                return result_t(NULL_OPTIONAL);
             }
         }
         else