diff --git a/Adapter.cc b/Adapter.cc
index 0641fb8..2fcc0ea 100644
--- a/Adapter.cc
+++ b/Adapter.cc
@@ -27,7 +27,7 @@ namespace pEp {
 
     messageToSend_t Adapter::_messageToSend = nullptr;
     notifyHandshake_t Adapter::_notifyHandshake = nullptr;
-    std::thread *_sync_thread = nullptr;
+    std::thread *Adapter::_sync_thread = nullptr;
 
     Adapter::Adapter(messageToSend_t messageToSend,
             notifyHandshake_t notifyHandshake, void *obj)
@@ -43,9 +43,9 @@ namespace pEp {
         {
             lock_guard<mutex> lock(mtx());
 
-            if (!_sync_thread) {
-                _sync_thread = new thread(sync_thread, obj);
-                _sync_thread->detach();
+            if (!Adapter::_sync_thread) {
+                Adapter::_sync_thread = new thread(sync_thread, obj);
+                Adapter::_sync_thread->detach();
             }
         }
     }
@@ -81,9 +81,11 @@ namespace pEp {
     void Adapter::shutdown()
     {
         _inject_sync_event(nullptr, nullptr);
-        _sync_thread->join();
-        delete _sync_thread;
-        _sync_thread = nullptr;
+        if (Adapter::_sync_thread) {
+            Adapter::_sync_thread->join();
+            delete Adapter::_sync_thread;
+            Adapter::_sync_thread = nullptr;
+        }
     }
 
     int Adapter::_inject_sync_event(SYNC_EVENT ev, void *management)
diff --git a/Adapter.hh b/Adapter.hh
index 44998b6..2bde67a 100644
--- a/Adapter.hh
+++ b/Adapter.hh
@@ -30,7 +30,7 @@ namespace pEp {
                 session(release);
             }
 
-            void shutdown();
+            static void shutdown();
 
         protected:
             static int _inject_sync_event(SYNC_EVENT ev, void *management);
diff --git a/Makefile b/Makefile
index 59038b4..ef06afa 100644
--- a/Makefile
+++ b/Makefile
@@ -10,16 +10,24 @@ CXXFLAGS += -I$(HOME)/include -std=c++14
 
 SOURCE=$(wildcard *.cc)
 OBJECTS=$(subst .cc,.o,$(SOURCE))
+WITHOUT_TESTS=$(patsubst test%.o,,$(OBJECTS))
 
 all: $(TARGET)
 
 %.o: %.cc %.hh
 	$(CXX) $(CXXFLAGS) -c $<
 
-$(TARGET): $(OBJECTS)
+$(TARGET): $(WITHOUT_TESTS)
 	ar -rc $@ $^
 
-.PHONY: clean
+.PHONY: clean test
 
 clean:
-	rm -f $(TARGET) $(OBJECTS)
+	rm -f $(TARGET) $(OBJECTS) *.a test_adapter
+
+test: test_adapter
+	./test_adapter
+
+test_adapter: $(OBJECTS)
+	$(CXX) -o $@ -L$(HOME)/lib -lpEpEngine $(OBJECTS)
+