diff --git a/Adapter.hh b/Adapter.hh
index d136f25..43f0f0c 100644
--- a/Adapter.hh
+++ b/Adapter.hh
@@ -1,7 +1,8 @@
 // This file is under GNU General Public License 3.0
 // see LICENSE.txt
 
-#pragma once
+#ifndef LIBPEPADAPTER_ADAPTER_HH
+#define LIBPEPADAPTER_ADAPTER_HH
 
 #include <functional>
 #include <string>
@@ -68,3 +69,5 @@ namespace pEp {
 }
 
 #include "Adapter.hxx"
+
+#endif  //LIBPEPADAPTER_ADAPTER_HH
\ No newline at end of file
diff --git a/Adapter.hxx b/Adapter.hxx
index a755075..2a2477f 100644
--- a/Adapter.hxx
+++ b/Adapter.hxx
@@ -1,7 +1,8 @@
 // This file is under GNU General Public License 3.0
 // see LICENSE.txt
 
-#pragma once
+#ifndef LIBPEPADAPTER_ADAPTER_HXX
+#define LIBPEPADAPTER_ADAPTER_HXX
 
 #include <thread>
 #include "locked_queue.hh"
@@ -35,11 +36,15 @@ namespace pEp {
                 _startup(obj);
             }
 
+            pEpLog("creating session");
             session();
 
             {
+                //TODO: Do we need to use a passphraseWrap here???
+                pEpLog("register_sync_callbacks()");
                 PEP_STATUS status = register_sync_callbacks(session(), nullptr,
                     _notifyHandshake, _retrieve_next_sync_event);
+                pEpLog("register_sync_callbacks() return:" << status);
                 try {
                     throw_status(status);
                     register_done.store(true);
@@ -100,3 +105,5 @@ namespace pEp {
         }
     }
 }
+
+#endif //LIBPEPADAPTER_ADAPTER_HXX
\ No newline at end of file
diff --git a/Semaphore.hh b/Semaphore.hh
index 0643372..268afa1 100644
--- a/Semaphore.hh
+++ b/Semaphore.hh
@@ -1,3 +1,9 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
+#ifndef LIBPEPADAPTER_SEMAPHORE_HH
+#define LIBPEPADAPTER_SEMAPHORE_HH
+
 #include <mutex>
 #include <condition_variable>
 
@@ -41,3 +47,6 @@ namespace pEp {
     };
 }
 
+#endif // LIBPEPADAPTER_SEMAPHORE_HH
+
+
diff --git a/call_with_lock.cc b/call_with_lock.cc
index cd04003..83ba416 100644
--- a/call_with_lock.cc
+++ b/call_with_lock.cc
@@ -1,4 +1,5 @@
-// this file is under GNU GPL 3.0, see LICENSE.txt
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
 
 #include "call_with_lock.hh"
 
diff --git a/call_with_lock.hh b/call_with_lock.hh
index 1877bcc..c8ebd73 100644
--- a/call_with_lock.hh
+++ b/call_with_lock.hh
@@ -1,7 +1,8 @@
-// this file is under GNU GPL 3.0, see LICENSE.txt
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
 
-#ifndef PEP_CALL_WITH_LOCK_HH
-#define PEP_CALL_WITH_LOCK_HH
+#ifndef LIBPEPADAPTER_CALL_WITH_LOCK_HH
+#define LIBPEPADAPTER_CALL_WITH_LOCK_HH
 
 #include <mutex>
 
@@ -22,4 +23,4 @@ namespace pEp
 
 }
 
-#endif // PEP_CALL_WITH_LOCK_HH
+#endif // LIBPEPADAPTER_CALL_WITH_LOCK_HH
diff --git a/callback_dispatcher.cc b/callback_dispatcher.cc
index 46d35dd..42a743c 100644
--- a/callback_dispatcher.cc
+++ b/callback_dispatcher.cc
@@ -1,3 +1,6 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
 #include "callback_dispatcher.hh"
 #include "passphrase_cache.hh"
 #include <stdexcept>
diff --git a/callback_dispatcher.hh b/callback_dispatcher.hh
index 818f5ef..54248cf 100644
--- a/callback_dispatcher.hh
+++ b/callback_dispatcher.hh
@@ -1,4 +1,8 @@
-#pragma once
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
+#ifndef LIBPEPADAPTER_CALLBACK_DISPATCHER_HH
+#define LIBPEPADAPTER_CALLBACK_DISPATCHER_HH
 
 #include <vector>
 #include <functional>
@@ -60,3 +64,4 @@ namespace pEp {
     extern CallbackDispatcher callback_dispatcher;
 }
 
+#endif // LIBPEPADAPTER_CALLBACK_DISPATCHER_HH
diff --git a/constant_time_algo.cc b/constant_time_algo.cc
index 6e4c2c4..8368b9e 100644
--- a/constant_time_algo.cc
+++ b/constant_time_algo.cc
@@ -1,3 +1,6 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
 #include "constant_time_algo.hh"
 
 namespace pEp
diff --git a/constant_time_algo.hh b/constant_time_algo.hh
index d9b7ae2..59463ac 100644
--- a/constant_time_algo.hh
+++ b/constant_time_algo.hh
@@ -1,4 +1,8 @@
-#pragma once
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
+#ifndef LIBPEPADAPTER_CONSTANT_TIME_ALGO_HH
+#define LIBPEPADAPTER_CONSTANT_TIME_ALGO_HH
 
 #include <string>
 
@@ -12,3 +16,5 @@ namespace pEp
     bool constant_time_equal(const std::string& a, const std::string& b);
 
 } // end of namespace pEp
+
+#endif // LIBPEPADAPTER_CONSTANT_TIME_ALGO_HH
diff --git a/locked_queue.hh b/locked_queue.hh
index ccf45ea..e440704 100644
--- a/locked_queue.hh
+++ b/locked_queue.hh
@@ -1,7 +1,8 @@
 // This file is under GNU General Public License 3.0
 // see LICENSE.txt
 
-#pragma once
+#ifndef LIBPEPADAPTER_LOCKED_QUEUE_HH
+#define LIBPEPADAPTER_LOCKED_QUEUE_HH
 
 #include <deque>
 #include <condition_variable>
@@ -182,3 +183,5 @@ namespace utility
     };
 
 } // end of namespace utility
+
+#endif // LIBPEPADAPTER_LOCKED_QUEUE_HH
diff --git a/message_cache.cc b/message_cache.cc
index fd8a28c..f507253 100644
--- a/message_cache.cc
+++ b/message_cache.cc
@@ -1,3 +1,6 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
 #include "message_cache.hh"
 #include <cassert>
 #include <cstring>
diff --git a/message_cache.hh b/message_cache.hh
index 7c3326d..b5c06be 100644
--- a/message_cache.hh
+++ b/message_cache.hh
@@ -1,4 +1,8 @@
-#pragma once
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
+#ifndef LIBPEPADAPTER_MESSAGE_CACHE_HH
+#define LIBPEPADAPTER_MESSAGE_CACHE_HH
 
 #include <string>
 #include <unordered_map>
@@ -128,3 +132,4 @@ namespace pEp {
     extern MessageCache message_cache;
 };
 
+#endif // LIBPEPADAPTER_MESSAGE_CACHE_HH
diff --git a/pEpLog.cc b/pEpLog.cc
index ec6f80d..006be68 100644
--- a/pEpLog.cc
+++ b/pEpLog.cc
@@ -1,3 +1,6 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
 #include "pEpLog.hh"
 #include <iostream> // cout and cerr
 #include <sstream> // for stringstream
diff --git a/pEpLog.hh b/pEpLog.hh
index e515db7..9970384 100644
--- a/pEpLog.hh
+++ b/pEpLog.hh
@@ -1,3 +1,6 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
 #ifndef LIBPEPADAPTER_PEPLOG_HH
 #define LIBPEPADAPTER_PEPLOG_HH
 
diff --git a/passphrase_cache.cc b/passphrase_cache.cc
index c3b46e9..ee170f2 100644
--- a/passphrase_cache.cc
+++ b/passphrase_cache.cc
@@ -1,3 +1,6 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
 #include <cassert>
 #include "Adapter.hh"
 #include "passphrase_cache.hh"
diff --git a/passphrase_cache.hh b/passphrase_cache.hh
index b857590..b514492 100644
--- a/passphrase_cache.hh
+++ b/passphrase_cache.hh
@@ -1,4 +1,8 @@
-#pragma once
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
+#ifndef LIBPEPADAPTER_PASSPHRASE_CACHE_HH
+#define LIBPEPADAPTER_PASSPHRASE_CACHE_HH
 
 #include <list>
 #include <string>
@@ -85,3 +89,4 @@ namespace pEp {
 
 #include "passphrase_cache.hxx"
 
+#endif // LIBPEPADAPTER_PASSPHRASE_CACHE_HH
diff --git a/passphrase_cache.hxx b/passphrase_cache.hxx
index cb97d7a..ad5c616 100644
--- a/passphrase_cache.hxx
+++ b/passphrase_cache.hxx
@@ -1,3 +1,9 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
+#ifndef LIBPEPADAPTER_PASSPHRASE_CACHE_HXX
+#define LIBPEPADAPTER_PASSPHRASE_CACHE_HXX
+
 #include "passphrase_cache.hh"
 
 namespace pEp {
@@ -20,3 +26,4 @@ namespace pEp {
     }
 };
 
+#endif // LIBPEPADAPTER_PASSPHRASE_CACHE_HXX
diff --git a/pc_container.hh b/pc_container.hh
index f470b92..d41e176 100644
--- a/pc_container.hh
+++ b/pc_container.hh
@@ -1,9 +1,10 @@
 // This file is under GNU General Public License 3.0
 // see LICENSE.txt
 
-#pragma once
+#ifndef LIBPEPADAPTER_PC_CONTAINER_HH
+#define LIBPEPADAPTER_PC_CONTAINER_HH
 
-// Conainer adapter that contains a container and a producer/consume queue
+// Container adapter that contains a container and a producer/consume queue
 // that holds references to all changed elements
 
 #include <functional>
@@ -82,4 +83,5 @@ private:
 };
 
 } // end of namespace pEp
+#endif // LIBPEPADAPTER_PC_CONTAINER_HH
 
diff --git a/slurp.cc b/slurp.cc
index 15519ab..a5cb3c5 100644
--- a/slurp.cc
+++ b/slurp.cc
@@ -1,3 +1,6 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
 #include "slurp.hh"
 #include <fstream>
 #include <sstream>
diff --git a/slurp.hh b/slurp.hh
index e990a99..7e65eaf 100644
--- a/slurp.hh
+++ b/slurp.hh
@@ -1,5 +1,8 @@
-#ifndef PEP_LIB_SLURP_HH
-#define PEP_LIB_SLURP_HH
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
+#ifndef LIBPEPADAPTER_LIB_SLURP_HH
+#define LIBPEPADAPTER_LIB_SLURP_HH
 
 #include <string>
 
@@ -11,4 +14,4 @@ namespace pEp
 
 } // end of namespace pEp
 
-#endif // PEP_LIB_SLURP_HH
\ No newline at end of file
+#endif // LIBPEPADAPTER_LIB_SLURP_HH
\ No newline at end of file
diff --git a/status_to_string.cc b/status_to_string.cc
index 123ed9e..c95e36e 100644
--- a/status_to_string.cc
+++ b/status_to_string.cc
@@ -1,3 +1,6 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
 #include "status_to_string.hh"
 #include <sstream>
 
diff --git a/status_to_string.hh b/status_to_string.hh
index e9ae835..5078ef3 100644
--- a/status_to_string.hh
+++ b/status_to_string.hh
@@ -1,4 +1,8 @@
-#pragma once
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
+#ifndef LIBPEPADAPTER_STATUS_TO_STRING_HH
+#define LIBPEPADAPTER_STATUS_TO_STRING_HH
 
 #include <pEp/pEpEngine.h>
 #include <pEp/status_to_string.h>
@@ -11,3 +15,5 @@ namespace pEp
     std::string status_to_string(PEP_STATUS status);
     
 } // end of namespace pEp
+
+#endif // LIBPEPADAPTER_STATUS_TO_STRING_HH
diff --git a/test/framework.hh b/test/framework.hh
index f0b28f7..05c5711 100644
--- a/test/framework.hh
+++ b/test/framework.hh
@@ -1,4 +1,7 @@
-#pragma once
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+#ifndef LIBPEPADAPTER_FRAMEWORK_HH
+#define LIBPEPADAPTER_FRAMEWORK_HH
 
 #include <string>
 #include <vector>
@@ -57,3 +60,4 @@ namespace pEp {
     };
 };
 
+#endif // LIBPEPADAPTER_FRAMEWORK_HH