diff --git a/src/client/xclient_messenger.cpp b/src/client/xclient_messenger.cpp
index b113ac7..2d6deda 100644
--- a/src/client/xclient_messenger.cpp
+++ b/src/client/xclient_messenger.cpp
@@ -47,4 +47,4 @@ namespace xeus
         m_heartbeat_controller.send(stop_msg, zmq::send_flags::none);
         (void)m_heartbeat_controller.recv(response);
     }
-}
\ No newline at end of file
+}
diff --git a/src/client/xclient_zmq_impl.cpp b/src/client/xclient_zmq_impl.cpp
index 9190762..f6c6db6 100644
--- a/src/client/xclient_zmq_impl.cpp
+++ b/src/client/xclient_zmq_impl.cpp
@@ -36,7 +36,11 @@ namespace xeus
 
     // Has to be in the cpp because incomplete
     // types are used in unique_ptr in the header
-    xclient_zmq_impl::~xclient_zmq_impl() = default;
+    xclient_zmq_impl::~xclient_zmq_impl()
+    {
+        m_iopub_thread.join();
+        m_heartbeat_thread.join();
+    }
 
     void xclient_zmq_impl::send_on_shell(xmessage msg)
     {
diff --git a/src/client/xheartbeat_client.cpp b/src/client/xheartbeat_client.cpp
index f84e3e9..b7a7327 100644
--- a/src/client/xheartbeat_client.cpp
+++ b/src/client/xheartbeat_client.cpp
@@ -7,6 +7,8 @@
 * The full license is in the file LICENSE, distributed with this software. *
 ****************************************************************************/
 
+#include <iostream>
+
 #include "xheartbeat_client.hpp"
 #include "xclient_zmq_impl.hpp"
 #include "../common/xmiddleware_impl.hpp"
@@ -23,6 +25,7 @@ namespace xeus
         , m_max_retry(max_retry)
         , m_heartbeat_timeout(timeout)
         , m_heartbeat_end_point("")
+        , m_request_stop(false)
     {
         m_heartbeat_end_point = get_end_point(config.m_transport, config.m_ip, config.m_hb_port);
         m_heartbeat.connect(m_heartbeat_end_point);
@@ -42,9 +45,35 @@ namespace xeus
 
     bool xheartbeat_client::wait_for_answer(long timeout)
     {
-        m_heartbeat.set(zmq::sockopt::linger, static_cast<int>(timeout));
-        zmq::message_t response;
-        return m_heartbeat.recv(response).has_value();
+        zmq::pollitem_t items[] = {
+            { m_heartbeat, 0, ZMQ_POLLIN, 0 }, { m_controller, 0, ZMQ_POLLIN, 0 }
+        };
+
+        zmq::poll(&items[0], 2, std::chrono::milliseconds(timeout));
+        try
+        {
+            if (items[0].revents & ZMQ_POLLIN)
+            {
+                zmq::multipart_t wire_msg;
+                wire_msg.recv(m_heartbeat);
+            }
+
+            if (items[1].revents & ZMQ_POLLIN)
+            {
+                // stop message
+                zmq::multipart_t wire_msg;
+                wire_msg.recv(m_controller);
+                wire_msg.send(m_controller);
+                m_request_stop = true;
+            }
+
+            return true;
+        }
+        catch (std::exception& e)
+        {
+            std::cerr << e.what() << std::endl;
+        }
+        return false;
     }
 
     void xheartbeat_client::register_kernel_status_listener(const kernel_status_listener& l)
@@ -59,10 +88,9 @@ namespace xeus
 
     void xheartbeat_client::run()
     {
-        bool stop = false;
         std::size_t retry_count = 0;
 
-        while(!stop)
+        while(!m_request_stop)
         {
             send_heartbeat_message();
             if(!wait_for_answer(m_heartbeat_timeout))
@@ -74,7 +102,7 @@ namespace xeus
                 else
                 {
                     notify_kernel_dead(true);
-                    stop = true;
+                    break;
                 }
             }
             else
diff --git a/src/client/xheartbeat_client.hpp b/src/client/xheartbeat_client.hpp
index f2500b0..0d1c228 100644
--- a/src/client/xheartbeat_client.hpp
+++ b/src/client/xheartbeat_client.hpp
@@ -48,7 +48,8 @@ namespace xeus
         const long m_heartbeat_timeout;
 
         std::string m_heartbeat_end_point;
+        bool m_request_stop;
     };
 }
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/client/xiopub_client.cpp b/src/client/xiopub_client.cpp
index 00158ef..5127b6f 100644
--- a/src/client/xiopub_client.cpp
+++ b/src/client/xiopub_client.cpp
@@ -59,7 +59,6 @@ namespace xeus
 
     void xiopub_client::run()
     {
-        zmq::multipart_t wire_msg;
         zmq::pollitem_t items[] = {
             { m_iopub, 0, ZMQ_POLLIN, 0 }, { m_controller, 0, ZMQ_POLLIN, 0 }
         };
@@ -71,6 +70,7 @@ namespace xeus
             {
                 if (items[0].revents & ZMQ_POLLIN)
                 {
+                    zmq::multipart_t wire_msg;
                     wire_msg.recv(m_iopub);
                     xpub_message msg = p_client_impl->deserialize_iopub(wire_msg);
                     {
@@ -80,15 +80,11 @@ namespace xeus
                 }
                 if (items[1].revents & ZMQ_POLLIN)
                 {
+                    // stop message
+                    zmq::multipart_t wire_msg;
                     wire_msg.recv(m_controller);
-                    if (wire_msg.size() > 0)
-                    {
-                        std::string received_msg = wire_msg.at(0).to_string();
-                        if (received_msg == "stop")
-                        {
-                            break;
-                        }
-                    }
+                    wire_msg.send(m_controller);
+                    break;
                 }
             }
             catch (std::exception& e)