Index: uspace/lib/cpp/include/impl/memory.hpp
===================================================================
--- uspace/lib/cpp/include/impl/memory.hpp	(revision 92cb73fd3066d4f0e5139d4d86e0a839b111a8e0)
+++ uspace/lib/cpp/include/impl/memory.hpp	(revision d2a66ae74301a90e120e736999161b58d5beaa1b)
@@ -53,4 +53,13 @@
 
     /**
+     * 20.7.6, allocator argument tag:
+     */
+
+    struct allocator_arg_t
+    { /* DUMMY BODY */ };
+
+    constexpr allocator_arg_t allocator_arg{};
+
+    /**
      * 20.7.8, allocator traits:
      */