diff --git a/Adapter.cc b/Adapter.cc
index 101b796..599edd9 100644
--- a/Adapter.cc
+++ b/Adapter.cc
@@ -30,7 +30,7 @@ namespace pEp {
     std::thread *_sync_thread = nullptr;
 
     Adapter::Adapter(messageToSend_t messageToSend,
-            notifyHandshake_t notifyHandshake)
+            notifyHandshake_t notifyHandshake, void *obj)
     {
         if (messageToSend)
             _messageToSend = messageToSend;
@@ -44,7 +44,7 @@ namespace pEp {
             lock_guard<mutex> lock(mtx());
 
             if (!_sync_thread)
-                _sync_thread = new thread();
+                _sync_thread = new thread(sync_thread, obj);
         }
     }
 
@@ -118,16 +118,17 @@ namespace pEp {
         return queue().pop_front();
     }
 
-    void Adapter::sync_thread()
+    void Adapter::sync_thread(void *obj)
     {
         PEP_STATUS status = register_sync_callbacks(session(), nullptr,
                 _notifyHandshake, _retrieve_next_sync_event);
         throw_status(status);
 
-        do_sync_protocol(session(), nullptr);
+        do_sync_protocol(session(), obj);
         unregister_sync_callbacks(session());
 
         session(release);
+        _sync_thread = nullptr;
     }
 }
 
diff --git a/Adapter.hh b/Adapter.hh
index 5919a97..ac9e7da 100644
--- a/Adapter.hh
+++ b/Adapter.hh
@@ -17,7 +17,7 @@ namespace pEp {
 
         public:
             Adapter(messageToSend_t messageToSend,
-                    notifyHandshake_t notifyHandshake);
+                    notifyHandshake_t notifyHandshake, void *obj = nullptr);
             virtual ~Adapter() { }
 
             enum session_action {
@@ -35,7 +35,7 @@ namespace pEp {
         protected:
             static int _inject_sync_event(SYNC_EVENT ev, void *management);
             static SYNC_EVENT _retrieve_next_sync_event(void *management, time_t threshold);
-            static void sync_thread();
+            static void sync_thread(void *obj);
 
         private:
             static std::mutex& mtx()