diff --git a/include/msgpack/v2/adaptor/adaptor_base.hpp b/include/msgpack/v2/adaptor/adaptor_base.hpp
index 09337681..be81d30b 100644
--- a/include/msgpack/v2/adaptor/adaptor_base.hpp
+++ b/include/msgpack/v2/adaptor/adaptor_base.hpp
@@ -32,7 +32,7 @@ struct pack : v1::adaptor::pack<T, Enabler> {
 };
 
 template <typename T, typename Enabler>
-struct object : v1::adaptor::object<T, Enabler> {
+struct object<T, Enabler, typename msgpack::enable_if<!msgpack::is_same<T, std::string>::value>::type> : v1::adaptor::object<T, Enabler> {
 };
 
 template <typename T, typename Enabler>
diff --git a/include/msgpack/v2/adaptor/adaptor_base_decl.hpp b/include/msgpack/v2/adaptor/adaptor_base_decl.hpp
index aa720924..cd24cb27 100644
--- a/include/msgpack/v2/adaptor/adaptor_base_decl.hpp
+++ b/include/msgpack/v2/adaptor/adaptor_base_decl.hpp
@@ -30,7 +30,7 @@ struct convert;
 template <typename T, typename Enabler = void>
 struct pack;
 
-template <typename T, typename Enabler = void>
+template <typename T, typename Enabler = void, typename Enabler2 = void>
 struct object;
 
 template <typename T, typename Enabler = void>
diff --git a/test/object_with_zone.cpp b/test/object_with_zone.cpp
index 9e3a80dd..eab3ac8b 100644
--- a/test/object_with_zone.cpp
+++ b/test/object_with_zone.cpp
@@ -316,6 +316,8 @@ TEST(object_with_zone, string)
     EXPECT_EQ(obj.as<string>()[0], 'a');
 }
 
+#if MSGPACK_DEFAULT_API_VERSION == 1
+
 TEST(object_without_zone, string)
 {
     string v = "abc";
@@ -326,6 +328,8 @@ TEST(object_without_zone, string)
     EXPECT_EQ(obj.as<string>()[0], 'd');
 }
 
+#endif // MSGPACK_DEFAULT_API_VERSION == 1
+
 // char*
 TEST(object_with_zone, char_ptr)
 {