diff --git a/src/shrpx_http2_session.cc b/src/shrpx_http2_session.cc
index 11b2a5f3..22e10935 100644
--- a/src/shrpx_http2_session.cc
+++ b/src/shrpx_http2_session.cc
@@ -196,6 +196,8 @@ int Http2Session::init_notification()
     SSLOG(FATAL, this) << "socketpair() failed: errno=" << errno;
     return -1;
   }
+  evutil_make_socket_nonblocking(sockpair[0]);
+  evutil_make_socket_nonblocking(sockpair[1]);
   wrbev_ = bufferevent_socket_new(evbase_, sockpair[0],
                                   BEV_OPT_CLOSE_ON_FREE|
                                   BEV_OPT_DEFER_CALLBACKS);
diff --git a/src/shrpx_listen_handler.cc b/src/shrpx_listen_handler.cc
index 7ef396d5..b4190235 100644
--- a/src/shrpx_listen_handler.cc
+++ b/src/shrpx_listen_handler.cc
@@ -67,6 +67,8 @@ void ListenHandler::create_worker_thread(size_t num)
       LLOG(ERROR, this) << "socketpair() failed: errno=" << errno;
       continue;
     }
+    evutil_make_socket_nonblocking(info->sv[0]);
+    evutil_make_socket_nonblocking(info->sv[1]);
     info->sv_ssl_ctx = sv_ssl_ctx_;
     info->cl_ssl_ctx = cl_ssl_ctx_;
     try {