diff --git a/Adapter.cc b/Adapter.cc
index 9b8ec34..f4a776d 100644
--- a/Adapter.cc
+++ b/Adapter.cc
@@ -11,6 +11,8 @@
 
 using namespace std;
 
+thread_local pEp::Adapter::Session pEp::Adapter::session;
+
 namespace pEp {
     void throw_status(PEP_STATUS status)
     {
@@ -87,25 +89,26 @@ namespace pEp {
             return _sync_thread.get_id() == this_thread::get_id();
         }
 
-        PEP_SESSION session(session_action action)
+        PEP_SESSION Session::operator()(session_action action)
         {
             std::lock_guard<mutex> lock(m);
             bool in_sync = on_sync_thread();
 
-            thread_local static PEP_SESSION _session = nullptr;
             PEP_STATUS status = PEP_STATUS_OK;
 
             switch (action) {
                 case release:
-                    if (_session) {
-                        ::release(_session);
+                    if (_session.get())
                         _session = nullptr;
-                    }
                     break;
 
                 case init:
-                    if (!_session)
-                        status = ::init(&_session, _messageToSend, _inject_sync_event, _ensure_passphrase);
+                    if (!_session.get()) {
+                        PEP_SESSION session_;
+                        status = ::init(&session_, _messageToSend, _inject_sync_event, _ensure_passphrase);
+                        throw_status(status);
+                        _session = SessionPtr{session_, ::release};
+                    }
                     break;
 
                 default:
@@ -113,7 +116,7 @@ namespace pEp {
             }
 
             throw_status(status);
-            return _session;
+            return _session.get();
         }
 
         void shutdown()
diff --git a/Adapter.hh b/Adapter.hh
index d71fb33..31eca44 100644
--- a/Adapter.hh
+++ b/Adapter.hh
@@ -7,6 +7,8 @@
 #include <string>
 #include <thread>
 #include <stdexcept>
+#include <memory>
+
 #include <pEp/sync_api.h>
 
 namespace pEp {
@@ -45,7 +47,16 @@ namespace pEp {
             init,
             release
         };
-        PEP_SESSION session(session_action action = init);
+
+        class Session {
+            using SessionPtr = std::unique_ptr<_pEpSession, std::function<void(PEP_SESSION)>>;
+            SessionPtr _session = nullptr;
+
+        public:
+            PEP_SESSION operator()(session_action action = init);
+        };
+
+        extern thread_local Session session;
 
         // injects a NULL event into sync_event_queue to denote sync thread to shutdown,
         // and joins & removes the sync thread
diff --git a/test/test_ensure_passphrase.cc b/test/test_ensure_passphrase.cc
index b096c1f..ef7146d 100644
--- a/test/test_ensure_passphrase.cc
+++ b/test/test_ensure_passphrase.cc
@@ -51,7 +51,7 @@ int main(int argc, char **argv)
     ::free_identity(bob);
     ::free_identity(erwin);
 
-    session(Adapter::release);
+    // session(Adapter::release);
 
     return 0;
 }
diff --git a/test/test_leave_device_group.cc b/test/test_leave_device_group.cc
index 756cc7d..368ead9 100644
--- a/test/test_leave_device_group.cc
+++ b/test/test_leave_device_group.cc
@@ -1,4 +1,5 @@
 #include <iostream>
+#include <vector>
 #include <unistd.h>
 
 #include "framework.hh"
@@ -11,19 +12,44 @@ using namespace pEp;
 using namespace pEp::Adapter;
 using namespace std;
 
+vector<string> expected_msg = {
+        "synchronizeGroupKeys",
+        "groupKeysUpdate",
+        "initUnledGroupKeyReset",
+        "beacon",
+        "beacon"
+    };
+
+vector<::sync_handshake_signal> expected_notification = {
+        SYNC_NOTIFY_IN_GROUP,
+        SYNC_NOTIFY_START,
+        SYNC_NOTIFY_SOLE,
+        SYNC_NOTIFY_START,
+        SYNC_NOTIFY_STOP
+    };
+
 PEP_STATUS test_messageToSend(::message *_msg)
 {
+    static auto actual = expected_msg.begin();
+
     Test::Message msg = Test::make_message(_msg);
-    cerr << Test::make_pEp_msg(msg);
+    string text = Test::make_pEp_msg(msg);
+    cerr << "expecting: " << *actual << endl;
+    cerr << text;
+    assert(text.find(*actual++) != string::npos);
     return PEP_STATUS_OK;   
 }
 
 
 PEP_STATUS test_notifyHandshake(pEp_identity *_me, pEp_identity *_partner, sync_handshake_signal signal)
 {
+    static auto actual = expected_notification.begin();
+
     Test::Identity me = Test::make_identity(_me);
     Test::Identity partner = Test::make_identity(_partner);
-
+    cerr << "expecting: " << *actual << endl;
+    cerr << "notifyHandshake: " << signal << endl;
+    assert(signal == *actual++);
     return PEP_STATUS_OK;   
 }
 
@@ -77,13 +103,16 @@ int main(int argc, char **argv)
     // wait for sync shutdown and release first session
 
     Test::join_sync_thread();
+    assert(!is_sync_running());
 
     // switch off and on again
 
     CallbackDispatcher::start_sync();
     sleep(2);
+    assert(is_sync_running());
     CallbackDispatcher::stop_sync();
     Test::join_sync_thread();
+    assert(!is_sync_running());
 
     session(Adapter::release);