use a separate type for None

1 files changed, 2 insertions, 2 deletions

diff --git a/promise.hpp b/promise.hpp
index 25fbd3b..3d38438 100644
--- a/promise.hpp
+++ b/promise.hpp
@@ -56,9 +56,9 @@ namespace promise {
     using bad_any_cast = boost::bad_any_cast;
 #endif
 
-    using None = std::nullptr_t;
+    struct None {};
     using values_t = std::vector<pm_any_t>;
-    const auto none = nullptr;
+    const auto none = None();
     const auto do_nothing = [](){};
 
     /* match lambdas */