diff --git a/include/__hash_table b/include/__hash_table
index 7b0fc412b..6157fcd99 100644
--- a/include/__hash_table
+++ b/include/__hash_table
@@ -112,6 +112,9 @@ public:
                                                          pointer;
 
     _LIBCPP_INLINE_VISIBILITY __hash_iterator() _NOEXCEPT
+#if _LIBCPP_STD_VER > 11
+    : __node_(nullptr)
+#endif
     {
 #if _LIBCPP_DEBUG_LEVEL >= 2
         __get_db()->__insert_i(this);
@@ -248,6 +251,9 @@ public:
     typedef __hash_iterator<__non_const_node_pointer> __non_const_iterator;
 
     _LIBCPP_INLINE_VISIBILITY __hash_const_iterator() _NOEXCEPT
+#if _LIBCPP_STD_VER > 11
+    : __node_(nullptr)
+#endif
     {
 #if _LIBCPP_DEBUG_LEVEL >= 2
         __get_db()->__insert_i(this);
diff --git a/test/containers/unord/unord.map/iterators.pass.cpp b/test/containers/unord/unord.map/iterators.pass.cpp
index 7d99fdf9d..4fc85a2a3 100644
--- a/test/containers/unord/unord.map/iterators.pass.cpp
+++ b/test/containers/unord/unord.map/iterators.pass.cpp
@@ -108,4 +108,18 @@ int main()
         C::const_iterator i;
     }
 #endif
+#if _LIBCPP_STD_VER > 11
+    { // N3664 testing
+        typedef std::unordered_map<int,double> C;
+        C::iterator ii1{}, ii2{};
+        C::iterator ii4 = ii1;
+        C::const_iterator cii{};
+        assert ( ii1 == ii2 );
+        assert ( ii1 == ii4 );
+        assert ( ii1 == cii );
+        
+        assert ( !(ii1 != ii2 ));
+        assert ( !(ii1 != cii ));
+    }
+#endif
 }
diff --git a/test/containers/unord/unord.multimap/iterators.pass.cpp b/test/containers/unord/unord.multimap/iterators.pass.cpp
index c2fc44bcb..cdf70c1a9 100644
--- a/test/containers/unord/unord.multimap/iterators.pass.cpp
+++ b/test/containers/unord/unord.multimap/iterators.pass.cpp
@@ -114,4 +114,18 @@ int main()
         C::const_iterator i;
     }
 #endif
+#if _LIBCPP_STD_VER > 11
+    { // N3664 testing
+        typedef std::unordered_multimap<int,double> C;
+        C::iterator ii1{}, ii2{};
+        C::iterator ii4 = ii1;
+        C::const_iterator cii{};
+        assert ( ii1 == ii2 );
+        assert ( ii1 == ii4 );
+        assert ( ii1 == cii );
+
+        assert ( !(ii1 != ii2 ));
+        assert ( !(ii1 != cii ));
+    }
+#endif
 }
diff --git a/test/containers/unord/unord.multiset/iterators.pass.cpp b/test/containers/unord/unord.multiset/iterators.pass.cpp
index ddfc3742f..bc6f88049 100644
--- a/test/containers/unord/unord.multiset/iterators.pass.cpp
+++ b/test/containers/unord/unord.multiset/iterators.pass.cpp
@@ -107,4 +107,18 @@ int main()
         C::const_iterator i;
     }
 #endif
+#if _LIBCPP_STD_VER > 11
+    { // N3664 testing
+        typedef std::unordered_multiset<int> C;
+        C::iterator ii1{}, ii2{};
+        C::iterator ii4 = ii1;
+        C::const_iterator cii{};
+        assert ( ii1 == ii2 );
+        assert ( ii1 == ii4 );
+        assert ( ii1 == cii );
+
+        assert ( !(ii1 != ii2 ));
+        assert ( !(ii1 != cii ));
+    }
+#endif
 }
diff --git a/test/containers/unord/unord.set/iterators.pass.cpp b/test/containers/unord/unord.set/iterators.pass.cpp
index 7815b9b38..6127d669b 100644
--- a/test/containers/unord/unord.set/iterators.pass.cpp
+++ b/test/containers/unord/unord.set/iterators.pass.cpp
@@ -107,4 +107,18 @@ int main()
         C::const_iterator i;
     }
 #endif
+#if _LIBCPP_STD_VER > 11
+    { // N3664 testing
+        typedef std::unordered_set<int> C;
+        C::iterator ii1{}, ii2{};
+        C::iterator ii4 = ii1;
+        C::const_iterator cii{};
+        assert ( ii1 == ii2 );
+        assert ( ii1 == ii4 );
+        assert ( ii1 == cii );
+
+        assert ( !(ii1 != ii2 ));
+        assert ( !(ii1 != cii ));
+    }
+#endif
 }