diff --git a/callback_dispatcher.cc b/callback_dispatcher.cc
index 1c54d47..6f4a3ce 100644
--- a/callback_dispatcher.cc
+++ b/callback_dispatcher.cc
@@ -29,7 +29,6 @@ namespace pEp {
             throw std::invalid_argument("messageToSend must be set");
 
         targets.push_back({messageToSend, notifyHandshake, on_startup, shutdown});
-        semaphore.go();
     }
 
     void CallbackDispatcher::remove(::messageToSend_t messageToSend)
diff --git a/callback_dispatcher.hh b/callback_dispatcher.hh
index 6ced956..17f39e3 100644
--- a/callback_dispatcher.hh
+++ b/callback_dispatcher.hh
@@ -5,6 +5,7 @@
 #include <mutex>
 #include "Adapter.hh"
 #include "Semaphore.hh"
+#include "passphrase_cache.hh"
 
 namespace pEp {
     // use this class when implementing a desktop adapter
@@ -46,6 +47,8 @@ namespace pEp {
         PEP_STATUS _messageToSend(::message *msg);
         PEP_STATUS _notifyHandshake(::pEp_identity *me,
                 ::pEp_identity *partner, ::sync_handshake_signal signal);
+
+        friend const char *PassphraseCache::add(const std::string& passphrase);
     };
 
     extern CallbackDispatcher callback_dispatcher;
diff --git a/passphrase_cache.cc b/passphrase_cache.cc
index 2aae276..45e10b1 100644
--- a/passphrase_cache.cc
+++ b/passphrase_cache.cc
@@ -1,6 +1,7 @@
 #include <cassert>
 #include "Adapter.hh"
 #include "passphrase_cache.hh"
+#include "callback_dispatcher.hh"
 
 pEp::PassphraseCache pEp::passphrase_cache;
 
@@ -35,15 +36,19 @@ namespace pEp {
     const char *PassphraseCache::add(const std::string& passphrase)
     {
         if (!passphrase.empty()) {
-            std::lock_guard<std::mutex> lock(_mtx);
-
-            while (_cache.size() >= _max_size)
-                _cache.pop_front();
-            
-            _cache.push_back({passphrase, clock::now()});
-            auto back = _cache.end();
-            assert(!_cache.empty());
-            auto result = (--back)->passphrase.c_str();
+            const char *result = nullptr;
+            {
+                std::lock_guard<std::mutex> lock(_mtx);
+
+                while (_cache.size() >= _max_size)
+                    _cache.pop_front();
+                
+                _cache.push_back({passphrase, clock::now()});
+                auto back = _cache.end();
+                assert(!_cache.empty());
+                result = (--back)->passphrase.c_str();
+            }
+            callback_dispatcher.semaphore.go();
             return result;
         }