diff --git a/src/asio_client_session_impl.h b/src/asio_client_session_impl.h
index 1cecedeb..c5c0e9ac 100644
--- a/src/asio_client_session_impl.h
+++ b/src/asio_client_session_impl.h
@@ -27,6 +27,8 @@
 
 #include "nghttp2_config.h"
 
+#include <boost/array.hpp>
+
 #include <nghttp2/asio_http2_client.h>
 
 namespace nghttp2 {
diff --git a/src/asio_client_stream.cc b/src/asio_client_stream.cc
index aa73413b..2d3aa5b9 100644
--- a/src/asio_client_stream.cc
+++ b/src/asio_client_stream.cc
@@ -40,9 +40,13 @@ void stream::stream_id(int32_t stream_id) { stream_id_ = stream_id; }
 
 int32_t stream::stream_id() const { return stream_id_; }
 
-request &stream::request() { return request_; }
+class request &stream::request() {
+  return request_;
+}
 
-response &stream::response() { return response_; }
+class response &stream::response() {
+  return response_;
+}
 
 session_impl *stream::session() const { return sess_; }
 
diff --git a/src/asio_client_stream.h b/src/asio_client_stream.h
index d61053c3..e3e027a0 100644
--- a/src/asio_client_stream.h
+++ b/src/asio_client_stream.h
@@ -47,8 +47,8 @@ public:
   void stream_id(int32_t stream_id);
   int32_t stream_id() const;
 
-  request &request();
-  response &response();
+  class request &request();
+  class response &response();
 
   session_impl *session() const;
 
diff --git a/src/asio_server_stream.cc b/src/asio_server_stream.cc
index 216fabe0..f763c1e0 100644
--- a/src/asio_server_stream.cc
+++ b/src/asio_server_stream.cc
@@ -40,9 +40,13 @@ stream::stream(http2_handler *h, int32_t stream_id)
 
 int32_t stream::get_stream_id() const { return stream_id_; }
 
-request &stream::request() { return request_; }
+class request &stream::request() {
+  return request_;
+}
 
-response &stream::response() { return response_; }
+class response &stream::response() {
+  return response_;
+}
 
 http2_handler *stream::handler() const { return handler_; }
 
diff --git a/src/asio_server_stream.h b/src/asio_server_stream.h
index e9dab447..cd7e081d 100644
--- a/src/asio_server_stream.h
+++ b/src/asio_server_stream.h
@@ -40,8 +40,8 @@ public:
   stream(http2_handler *h, int32_t stream_id);
 
   int32_t get_stream_id() const;
-  request &request();
-  response &response();
+  class request &request();
+  class response &response();
 
   http2_handler *handler() const;