diff --git a/xo-alloc/include/xo/alloc/Object.hpp b/xo-alloc/include/xo/alloc/Object.hpp
index a29b8de5..5727331e 100644
--- a/xo-alloc/include/xo/alloc/Object.hpp
+++ b/xo-alloc/include/xo/alloc/Object.hpp
@@ -39,6 +39,11 @@ namespace xo {
         template <typename S>
         gc_ptr(const gc_ptr<S> & x) : ptr_{x.ptr()} {}
 
+        /** convenience for static asserts **/
+        static constexpr bool is_gc_ptr = true;
+        /** see also: xo/refcnt/Refcounted.hpp **/
+        static constexpr bool is_rc_ptr = false;
+
         static bool is_eq(gc_ptr x1, gc_ptr x2) {
             std::uintptr_t u1 = reinterpret_cast<std::uintptr_t>(x1.ptr());
             std::uintptr_t u2 = reinterpret_cast<std::uintptr_t>(x2.ptr());
diff --git a/xo-refcnt/include/xo/refcnt/Refcounted.hpp b/xo-refcnt/include/xo/refcnt/Refcounted.hpp
index 732acb0b..622f2a74 100644
--- a/xo-refcnt/include/xo/refcnt/Refcounted.hpp
+++ b/xo-refcnt/include/xo/refcnt/Refcounted.hpp
@@ -80,6 +80,11 @@ namespace xo {
                 x.ptr_ = nullptr;
             }
 
+            /** convenience tests for static_assert() **/
+            static constexpr bool is_rc_ptr = true;
+            /** see also: xo/alloc/Object.hpp **/
+            static constexpr bool is_gc_ptr = false;
+
             /* aliasing ctor.  see ctor (8) here:
              *   [[https://en.cppreference.com/w/cpp/memory/shared_ptr/shared_ptr]]
              * and this dicsussion: