diff --git a/include/msgpack/adaptor/map.hpp b/include/msgpack/adaptor/map.hpp
index 5cbb6ede..464af7e4 100644
--- a/include/msgpack/adaptor/map.hpp
+++ b/include/msgpack/adaptor/map.hpp
@@ -94,7 +94,7 @@ inline void operator<< (object::with_zone& o, const type::assoc_vector<K,V>& v)
 
 
 template <typename K, typename V>
-inline std::map<K, V> operator>> (object const& o, std::map<K, V>& v)
+inline std::map<K, V>& operator>> (object const& o, std::map<K, V>& v)
 {
     if(o.type != type::MAP) { throw type_error(); }
     object_kv* p(o.via.map.ptr);
@@ -150,7 +150,7 @@ inline void operator<< (object::with_zone& o, const std::map<K,V>& v)
 
 
 template <typename K, typename V>
-inline std::multimap<K, V> operator>> (object const& o, std::multimap<K, V>& v)
+inline std::multimap<K, V>& operator>> (object const& o, std::multimap<K, V>& v)
 {
     if(o.type != type::MAP) { throw type_error(); }
     object_kv* p(o.via.map.ptr);
@@ -202,4 +202,3 @@ inline void operator<< (object::with_zone& o, const std::multimap<K,V>& v)
 }  // namespace msgpack
 
 #endif /* msgpack/type/map.hpp */
-
diff --git a/include/msgpack/adaptor/tr1/unordered_map.hpp b/include/msgpack/adaptor/tr1/unordered_map.hpp
index 7d8a18e8..b18af70f 100644
--- a/include/msgpack/adaptor/tr1/unordered_map.hpp
+++ b/include/msgpack/adaptor/tr1/unordered_map.hpp
@@ -44,7 +44,7 @@ namespace msgpack {
 
 
 template <typename K, typename V>
-inline MSGPACK_STD_TR1::unordered_map<K, V> operator>> (object o, MSGPACK_STD_TR1::unordered_map<K, V>& v)
+inline MSGPACK_STD_TR1::unordered_map<K, V>& operator>> (object o, MSGPACK_STD_TR1::unordered_map<K, V>& v)
 {
     if(o.type != type::MAP) { throw type_error(); }
     object_kv* p(o.via.map.ptr);
@@ -93,7 +93,7 @@ inline void operator<< (object::with_zone& o, const MSGPACK_STD_TR1::unordered_m
 
 
 template <typename K, typename V>
-inline MSGPACK_STD_TR1::unordered_multimap<K, V> operator>> (object o, MSGPACK_STD_TR1::unordered_multimap<K, V>& v)
+inline MSGPACK_STD_TR1::unordered_multimap<K, V>& operator>> (object o, MSGPACK_STD_TR1::unordered_multimap<K, V>& v)
 {
     if(o.type != type::MAP) { throw type_error(); }
     object_kv* p(o.via.map.ptr);
@@ -147,4 +147,3 @@ inline void operator<< (object::with_zone& o, const MSGPACK_STD_TR1::unordered_m
 #undef MSGPACK_STD_TR1
 
 #endif /* msgpack/type/map.hpp */
-