diff --git a/extras/test.cpp b/extras/test.cpp
index a02a1d1..df34b1b 100644
--- a/extras/test.cpp
+++ b/extras/test.cpp
@@ -11,6 +11,7 @@
 #include <string>
 #include <vector>
 #include <set>
+#include <unordered_map>
 
 namespace stdcpp {
     namespace test {
@@ -37,3 +38,6 @@ template std::size_t stdcpp::test::cppSizeOf<std::vector<int> >();
 
 template class std::set<int>;
 template std::size_t stdcpp::test::cppSizeOf<std::set<int> >();
+
+template class std::unordered_map<int, char>;
+template std::size_t stdcpp::test::cppSizeOf<std::unordered_map<int, char> >();
diff --git a/source/stdcpp/Hashtable.d b/source/stdcpp/Hashtable.d
new file mode 100644
index 0000000..891db07
--- /dev/null
+++ b/source/stdcpp/Hashtable.d
@@ -0,0 +1,98 @@
+/**
+ * D header file for C++ Hashtable for unordered_map.
+ *
+ * Copyright: Copyright (c) 2018 D Language Foundation
+ * License: Distributed under the
+ *      $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost Software License 1.0).
+ *    (See accompanying file LICENSE)
+ * Authors:   Emmanuel Nyarko
+ *            
+ */
+module stdcpp.Hashtable;
+
+import stdcpp.allocator;
+import stdcpp.utility : pair;
+import stdcpp.xutility : StdNamespace;
+
+extern(C++, (StdNamespace)):
+
+version (CppRuntime_Gcc)
+{
+    /**
+     * structs for hashtable template arguments to get the right mangling           
+     */
+    struct hash(T)
+    {
+    }
+
+    struct equal_to(T = void)
+    {
+    }
+
+    extern(C++, "__detail") struct _Select1st
+    {
+    }
+
+    extern(C++, "__detail") struct _Mod_range_hashing
+    {
+    }
+
+    extern(C++, "__detail") struct _Default_ranged_hash
+    {
+    }
+
+    extern(C++, "__detail") struct _Prime_rehash_policy
+    {
+    }
+
+    extern(C++, "__detail") struct _Hashtable_traits(bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys)
+    {
+        import stdcpp.type_traits : bool_constant;
+        alias __hash_cached = bool_constant!(_Cache_hash_code);
+    }
+
+    extern(C++, "__detail") struct _Hashtable_alloc(_NodeAlloc)
+    {
+        alias __node_base = _Hash_node_base;
+        alias __node_base_ptr = __node_base*;
+        alias __buckets_ptr = __node_base_ptr*;
+    }
+
+    extern(C++, "__detail") struct _Hash_node_base
+    {
+        _Hash_node_base* _M_next;
+    }
+
+    extern(C++, "__detail") struct _Hash_node(_Value, bool _Cache_hash_code)
+    {
+        _Hash_node_base __hb;
+    }
+
+    alias __umap_traits(bool _cache) = _Hashtable_traits!(_cache, false, true);
+
+    alias __umap_hashtable(_Key, _Tp, _Hash, _Pred, Alloc, _Tr = __umap_traits!(false)) = _Hashtable!(_Key, pair!(const(_Key), _Tp), Alloc, _Select1st, _Pred, _Hash,
+                                                                                _Mod_range_hashing, _Default_ranged_hash, _Prime_rehash_policy, _Tr );
+    extern(C++, class) struct _Hashtable(_Key, _Value, _Alloc, _ExtractKey, _Equal,
+                                         _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits)
+    {
+        alias size_type = size_t;
+        alias __traits_type = _Traits;
+        alias __hash_cached = __traits_type.__hash_cached;
+        alias __node_type = _Hash_node!(_Value, __hash_cached.value);
+        alias __node_alloc_type = allocator_traits!(_Alloc).rebind_alloc!(__node_type);
+        alias __hashtable_alloc = _Hashtable_alloc!(__node_alloc_type);
+        alias __node_base = __hashtable_alloc.__node_base;
+        alias __buckets_ptr = __hashtable_alloc.__buckets_ptr;
+        alias __node_base_ptr = __hashtable_alloc.__node_base_ptr;
+    
+    private:
+
+        __buckets_ptr _M_buckets;
+        size_type _M_bucket_count = 1;
+        __node_base _M_before_begin;
+        size_type _M_element_count = 0;
+        _RehashPolicy _M_rehash_policy;
+        __node_base_ptr _M_single_bucket;
+        void* _M_void;
+    }
+}
diff --git a/source/stdcpp/unordered_map.d b/source/stdcpp/unordered_map.d
index bb3aa33..8a85f04 100644
--- a/source/stdcpp/unordered_map.d
+++ b/source/stdcpp/unordered_map.d
@@ -101,3 +101,7 @@ extern(C++, class) struct unordered_map(Key, value, Hash, KeyEqual, Alloc)
     private _Hashtable _M_h;
     }
 }
+else version(CppRuntime_Micorosoft)
+{
+    static assert(0, "CpppRuntime not yet supported");
+}