diff --git a/src/sync_mixin.cc b/src/sync_mixin.cc
index 051d541..8df8369 100644
--- a/src/sync_mixin.cc
+++ b/src/sync_mixin.cc
@@ -4,13 +4,17 @@
 
 namespace pEp {
     namespace PythonAdapter {
-        void SyncMixIn::register_for_keysync()
+        SyncMixIn::SyncMixIn()
         {
             PEP_STATUS status = register_sync_callbacks(session, (void *) this,
                     messageToSend, showHandshake);
             assert(status == PEP_STATUS_OK);
         }
 
+        SyncMixIn::~SyncMixIn() {
+            unregister_sync_callbacks(session);
+        }
+
         PEP_STATUS SyncMixIn::messageToSend(void *obj, const message *msg)
         {
             SyncMixIn *that = (SyncMixIn *) obj;
diff --git a/src/sync_mixin.hh b/src/sync_mixin.hh
index ae3b865..733a5be 100644
--- a/src/sync_mixin.hh
+++ b/src/sync_mixin.hh
@@ -6,8 +6,8 @@ namespace pEp {
     namespace PythonAdapter {
         class SyncMixIn {
             public:
-                virtual ~SyncMixIn() { }
-                void register_for_keysync();
+                SyncMixIn();
+                virtual ~SyncMixIn();
 
             protected:
                 static PEP_STATUS messageToSend(void *obj, const message *msg);