diff --git a/libs/react/include/psemek/react/map.hpp b/libs/react/include/psemek/react/map.hpp
index b8f26017..e1ce86ad 100644
--- a/libs/react/include/psemek/react/map.hpp
+++ b/libs/react/include/psemek/react/map.hpp
@@ -81,6 +81,8 @@ namespace psemek::react
 
 			for (auto const & arg : args)
 			{
+				if (!arg) continue;
+
 				internal_tokens.push_back(arg.subscribe(detail::internal_tag{}, internal_subscriber));
 				external_tokens.push_back(arg.subscribe(external_subscriber));
 			}