diff --git a/include/__config b/include/__config
index e28fc5d..bb36244 100644
--- a/include/__config
+++ b/include/__config
@@ -756,7 +756,7 @@
 #  elif __cplusplus <= 201402L
 #    define _LIBCPP_STD_VER 14
 #  else
-#    define _LIBCPP_STD_VER 15  // current year, or date of c++17 ratification
+#    define _LIBCPP_STD_VER 16  // current year, or date of c++17 ratification
 #  endif
 #endif  // _LIBCPP_STD_VER
 
diff --git a/include/memory b/include/memory
index 47963e0..50a1f00 100644
--- a/include/memory
+++ b/include/memory
@@ -361,6 +361,7 @@
 {
 public:
     typedef T element_type;
+    typedef weak_ptr<T> weak_type; // C++17
 
     // constructors:
     constexpr shared_ptr() noexcept;
@@ -3863,6 +3864,9 @@
 {
 public:
     typedef _Tp element_type;
+#if _LIBCPP_STD_VER > 14
+    typedef weak_ptr<_Tp> weak_type;
+#endif
 private:
     element_type*      __ptr_;
     __shared_weak_count* __cntrl_;
diff --git a/test/std/utilities/memory/util.smartptr/util.smartptr.shared/types.pass.cpp b/test/std/utilities/memory/util.smartptr/util.smartptr.shared/types.pass.cpp
index 8175312..f44c05e 100644
--- a/test/std/utilities/memory/util.smartptr/util.smartptr.shared/types.pass.cpp
+++ b/test/std/utilities/memory/util.smartptr/util.smartptr.shared/types.pass.cpp
@@ -13,14 +13,20 @@
 // {
 // public:
 //     typedef T element_type;
+//     typedef weak_ptr<T> weak_type; // C++17
 //     ...
 // };
 
 #include <memory>
 
+#include "test_macros.h"
+
 struct A;  // purposefully incomplete
 
 int main()
 {
     static_assert((std::is_same<std::shared_ptr<A>::element_type, A>::value), "");
+#if TEST_STD_VER > 14
+    static_assert((std::is_same<std::shared_ptr<A>::weak_type, std::weak_ptr<A>>::value), "");
+#endif
 }
diff --git a/test/support/test_macros.h b/test/support/test_macros.h
index ada4a96..a072e31 100644
--- a/test/support/test_macros.h
+++ b/test/support/test_macros.h
@@ -43,7 +43,7 @@
 #elif __cplusplus <= 201402L
 # define TEST_STD_VER 14
 #else
-# define TEST_STD_VER 99    // greater than current standard
+# define TEST_STD_VER 16    // current year; greater than current standard
 #endif
 #endif