diff --git a/core/AmB2BMedia.cpp b/core/AmB2BMedia.cpp
index b57a846a..288aee21 100644
--- a/core/AmB2BMedia.cpp
+++ b/core/AmB2BMedia.cpp
@@ -44,7 +44,7 @@ void B2BMediaStatistics::incCodecWriteUsage(const string &codec_name)
 {
   if (codec_name.empty()) return;
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   map<string, int>::iterator i = codec_write_usage.find(codec_name);
   if (i != codec_write_usage.end()) i->second++;
   else codec_write_usage[codec_name] = 1;
@@ -54,7 +54,7 @@ void B2BMediaStatistics::decCodecWriteUsage(const string &codec_name)
 {
   if (codec_name.empty()) return;
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   map<string, int>::iterator i = codec_write_usage.find(codec_name);
   if (i != codec_write_usage.end()) {
     if (i->second > 0) i->second--;
@@ -65,7 +65,7 @@ void B2BMediaStatistics::incCodecReadUsage(const string &codec_name)
 {
   if (codec_name.empty()) return;
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   map<string, int>::iterator i = codec_read_usage.find(codec_name);
   if (i != codec_read_usage.end()) i->second++;
   else codec_read_usage[codec_name] = 1;
@@ -75,7 +75,7 @@ void B2BMediaStatistics::decCodecReadUsage(const string &codec_name)
 {
   if (codec_name.empty()) return;
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   map<string, int>::iterator i = codec_read_usage.find(codec_name);
   if (i != codec_read_usage.end()) {
     if (i->second > 0) i->second--;
@@ -96,7 +96,7 @@ void B2BMediaStatistics::reportCodecWriteUsage(string &dst)
 
   bool first = true;
   dst.clear();
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   for (map<string, int>::iterator i = codec_write_usage.begin();
       i != codec_write_usage.end(); ++i) 
   {
@@ -117,7 +117,7 @@ void B2BMediaStatistics::reportCodecReadUsage(string &dst)
 
   bool first = true;
   dst.clear();
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   for (map<string, int>::iterator i = codec_read_usage.begin();
       i != codec_read_usage.end(); ++i) 
   {
@@ -135,7 +135,7 @@ void B2BMediaStatistics::getReport(const AmArg &args, AmArg &ret)
   AmArg read_usage;
 
   { // locked area
-    AmLock lock(mutex);
+    lock_guard<AmMutex> lock(mutex);
 
     for (map<string, int>::iterator i = codec_write_usage.begin();
         i != codec_write_usage.end(); ++i) 
@@ -548,7 +548,7 @@ bool AmB2BMedia::releaseReference() {
 
 void AmB2BMedia::changeSession(bool a_leg, AmB2BSession *new_session)
 {
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   changeSessionUnsafe(a_leg, new_session);
 }
 
@@ -610,7 +610,7 @@ void AmB2BMedia::changeSessionUnsafe(bool a_leg, AmB2BSession *new_session)
 int AmB2BMedia::writeStreams(unsigned long long ts, unsigned char *buffer)
 {
   int res = 0;
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   for (AudioStreamIterator i = audio.begin(); i != audio.end(); ++i) {
     if (i->a.writeStream(ts, buffer, i->b) < 0) { res = -1; break; }
     if (i->b.writeStream(ts, buffer, i->a) < 0) { res = -1; break; }
@@ -620,7 +620,7 @@ int AmB2BMedia::writeStreams(unsigned long long ts, unsigned char *buffer)
 
 void AmB2BMedia::processDtmfEvents()
 {
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   for (AudioStreamIterator i = audio.begin(); i != audio.end(); ++i) {
     i->a.processDtmfEvents();
     i->b.processDtmfEvents();
@@ -632,7 +632,7 @@ void AmB2BMedia::processDtmfEvents()
 
 void AmB2BMedia::sendDtmf(bool a_leg, int event, unsigned int duration_ms)
 {
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   if(!audio.size())
     return;
 
@@ -648,7 +648,7 @@ void AmB2BMedia::sendDtmf(bool a_leg, int event, unsigned int duration_ms)
 void AmB2BMedia::clearAudio(bool a_leg)
 {
   TRACE("clear %s leg audio\n", a_leg ? "A" : "B");
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
 
   for (AudioStreamIterator i = audio.begin(); i != audio.end(); ++i) {
     // remove streams from AmRtpReceiver first! (always both?)
@@ -685,7 +685,7 @@ void AmB2BMedia::clearAudio(bool a_leg)
 
 void AmB2BMedia::clearRTPTimeout()
 {
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
 
   for (AudioStreamIterator i = audio.begin(); i != audio.end(); ++i) {
     i->a.clearRTPTimeout();
@@ -740,7 +740,7 @@ void AmB2BMedia::replaceConnectionAddress(AmSdp &parser_sdp, bool a_leg,
                                           const string& relay_address,
                                           const string& relay_public_address)
 {
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
 
   /* needed for the 'quick workaround' for non-audio media */
   SdpConnection orig_conn = parser_sdp.conn;
@@ -1005,7 +1005,7 @@ void AmB2BMedia::updateStreams(bool a_leg, const AmSdp &local_sdp, const AmSdp &
     INFO("remote SDP: %s\n", s.c_str());
   */
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   /* streams should be created already (replaceConnectionAddress called
      before updateLocalSdp uses/assignes their port numbers) */
 
@@ -1101,7 +1101,7 @@ bool AmB2BMedia::replaceOffer(AmSdp &sdp, bool a_leg)
   TRACE("replacing offer with a local one\n");
   createStreams(sdp); // create missing streams
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
 
   try {
 
@@ -1134,7 +1134,7 @@ bool AmB2BMedia::replaceOffer(AmSdp &sdp, bool a_leg)
 
 void AmB2BMedia::setMuteFlag(bool a_leg, bool set)
 {
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   if (a_leg) a_leg_muted = set;
   else b_leg_muted = set;
   for (AudioStreamIterator i = audio.begin(); i != audio.end(); ++i) {
@@ -1145,7 +1145,7 @@ void AmB2BMedia::setMuteFlag(bool a_leg, bool set)
 
 void AmB2BMedia::setFirstStreamInput(bool a_leg, AmAudio *in)
 {
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
   //for ( i != audio.end(); ++i) {
   if (!audio.empty()) {
     AudioStreamIterator i = audio.begin();
@@ -1170,7 +1170,7 @@ void AmB2BMedia::createHoldAnswer(bool a_leg, const AmSdp &offer, AmSdp &answer,
   // non-disabled stream in the response so we can not set all ports to 0 to
   // signalize that we don't want to receive anything)
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
 
   answer = offer;
   answer.media.clear();
@@ -1220,7 +1220,7 @@ void AmB2BMedia::setRtpLogger(msg_logger* _logger)
 
 void AmB2BMedia::setRelayDTMFReceiving(bool enabled) {
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
 
   DBG("relay_streams.size() = %zd, audio_streams.size() = %zd\n", relay_streams.size(), audio.size());
   for (RelayStreamIterator j = relay_streams.begin(); j != relay_streams.end(); j++) {
@@ -1244,7 +1244,7 @@ void AmB2BMedia::setRelayDTMFReceiving(bool enabled) {
 /** set receving of RTP/relay streams (not receiving=drop incoming packets) */
 void AmB2BMedia::setReceiving(bool receiving_a, bool receiving_b) {
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
 
   DBG("relay_streams.size() = %zd, audio_streams.size() = %zd\n", relay_streams.size(), audio.size());
   for (RelayStreamIterator j = relay_streams.begin(); j != relay_streams.end(); j++) {
@@ -1265,7 +1265,7 @@ void AmB2BMedia::setReceiving(bool receiving_a, bool receiving_b) {
 
 void AmB2BMedia::pauseRelay() {
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
 
   DBG("relay_streams.size() = %zd, audio_streams.size() = %zd\n", relay_streams.size(), audio.size());
   relay_paused = true;
@@ -1282,7 +1282,7 @@ void AmB2BMedia::pauseRelay() {
 
 void AmB2BMedia::restartRelay() {
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
 
   DBG("relay_streams.size() = %zd, audio_streams.size() = %zd\n", relay_streams.size(), audio.size());
   relay_paused = false;
@@ -1311,7 +1311,7 @@ void AudioStreamData::debug()
 void AmB2BMedia::debug()
 {
 
-  AmLock lock(mutex);
+  lock_guard<AmMutex> lock(mutex);
 
   // walk through all the streams
   DBG("B2B media session %p ('%s' <-> '%s'):",
diff --git a/core/AmSessionContainer.cpp b/core/AmSessionContainer.cpp
index 1f5248e1..ae6e6cbd 100644
--- a/core/AmSessionContainer.cpp
+++ b/core/AmSessionContainer.cpp
@@ -381,7 +381,7 @@ bool AmSessionContainer::postEvent(const string& local_tag,
 
 void AmSessionContainer::setCPSLimit(unsigned int limit)
 {
-  AmLock lock(cps_mut);
+  lock_guard<AmMutex> lock(cps_mut);
   CPSLimit = CPSHardLimit = limit;
 }
 
@@ -395,7 +395,7 @@ void AmSessionContainer::setCPSSoftLimit(unsigned int percent)
   struct timeval tv, res;
   gettimeofday(&tv,0);
 
-  AmLock lock(cps_mut);
+  lock_guard<AmMutex> lock(cps_mut);
 
   while (cps_queue.size()) {
     timersub(&tv, &cps_queue.front(), &res);
@@ -412,7 +412,7 @@ void AmSessionContainer::setCPSSoftLimit(unsigned int percent)
 
 pair<unsigned int, unsigned int> AmSessionContainer::getCPSLimit()
 {
-  AmLock lock(cps_mut);
+  lock_guard<AmMutex> lock(cps_mut);
   return pair<unsigned int, unsigned int>(CPSHardLimit, CPSLimit);
 }
 
@@ -421,7 +421,7 @@ unsigned int AmSessionContainer::getAvgCPS()
   struct timeval tv, res;
   gettimeofday(&tv,0);
 
-  AmLock lock(cps_mut);
+  lock_guard<AmMutex> lock(cps_mut);
 
   while (cps_queue.size()) {
     timersub(&tv, &cps_queue.front(), &res);
@@ -438,7 +438,7 @@ unsigned int AmSessionContainer::getAvgCPS()
 
 unsigned int AmSessionContainer::getMaxCPS()
 {
-  AmLock lock(cps_mut);
+  lock_guard<AmMutex> lock(cps_mut);
   unsigned int res = max_cps;
   max_cps = 0;
   return res;
@@ -453,7 +453,7 @@ bool AmSessionContainer::check_and_add_cps(bool emergency_flag)
   struct timeval tv, res;
   gettimeofday(&tv,0);
 
-  AmLock lock(cps_mut);
+  lock_guard<AmMutex> lock(cps_mut);
 
   // check global policy for dropping emergency calls
   if (!AmConfig::skip_cpslimit_emergency && emergency_flag) {
diff --git a/core/AmThread.cpp b/core/AmThread.cpp
index c33a0fc0..faf38fe5 100644
--- a/core/AmThread.cpp
+++ b/core/AmThread.cpp
@@ -111,10 +111,9 @@ void AmThread::start()
 
 void AmThread::stop()
 {
-  _m_td.lock();
+  lock_guard<AmMutex> _l(_m_td);
 
   if(is_stopped()){
-    _m_td.unlock();
     return;
   }
 
@@ -138,12 +137,10 @@ void AmThread::stop()
   DBG("Thread %lu (%lu) finished detach.\n", (unsigned long int) _pid, (unsigned long int) _td);
 
   //pthread_cancel(_td);
-
-  _m_td.unlock();
 }
 
 void AmThread::cancel() {
-  _m_td.lock();
+  lock_guard<AmMutex> _l(_m_td);
 
   int res;
   if ((res = pthread_cancel(_td)) != 0) {
@@ -152,8 +149,6 @@ void AmThread::cancel() {
     DBG("Thread %lu is canceled.\n", (unsigned long int) _pid);
     _stopped.set(true);
   }
-
-  _m_td.unlock();
 }
 
 void AmThread::join()
diff --git a/core/AmThread.h b/core/AmThread.h
index 5ad448ef..35190144 100644
--- a/core/AmThread.h
+++ b/core/AmThread.h
@@ -34,6 +34,9 @@
 #include <errno.h>
 
 #include <queue>
+#include <mutex>
+
+using std::lock_guard;
 
 /**
  * \brief C++ Wrapper class for pthread mutex
@@ -49,21 +52,6 @@ public:
   void unlock();
 };
 
-/**
- * \brief  Simple lock class
- */
-class AmLock
-{
-  AmMutex& m;
-public:
-  AmLock(AmMutex& _m) : m(_m) {
-    m.lock();
-  }
-  ~AmLock(){
-    m.unlock();
-  }
-};
-
 /**
  * \brief Shared variable.
  *
diff --git a/core/log.cpp b/core/log.cpp
index 933657e3..9e794597 100644
--- a/core/log.cpp
+++ b/core/log.cpp
@@ -202,7 +202,7 @@ void run_log_hooks(int level, pid_t pid, pthread_t tid, const char* func, const
  */
 void register_log_hook(AmLoggingFacility* fac)
 {
-  AmLock lock(log_hooks_mutex);
+  lock_guard<AmMutex> lock(log_hooks_mutex);
   log_hooks.push_back(fac);
 }
 
diff --git a/core/sip/async_file.cpp b/core/sip/async_file.cpp
index f12bc65f..b4252270 100644
--- a/core/sip/async_file.cpp
+++ b/core/sip/async_file.cpp
@@ -41,7 +41,7 @@ async_file::~async_file()
 
 int async_file::write(const void* buf, unsigned int len)
 {
-  AmLock _l(*this);
+  lock_guard<AmMutex> _l(*this);
   if(closed) return Closed;
   if(error)  return Error;
 
@@ -58,7 +58,7 @@ int async_file::write(const void* buf, unsigned int len)
 
 int async_file::writev(const struct iovec *iov, int iovcnt)
 {
-  AmLock _l(*this);
+  lock_guard<AmMutex> _l(*this);
   if(closed) return Closed;
   if(error)  return Error;
 
@@ -75,7 +75,7 @@ int async_file::writev(const struct iovec *iov, int iovcnt)
 
 void async_file::close()
 {
-  AmLock _l(*this);
+  lock_guard<AmMutex> _l(*this);
   closed = true;
   event_active(ev_write, 0, 0);
 }
@@ -120,6 +120,6 @@ void async_file::write_cycle()
 
 unsigned int async_file::get_buffered_bytes()
 {
-  AmLock _l(*this);
+  lock_guard<AmMutex> _l(*this);
   return fifo_buffer::get_buffered_bytes();
 }
diff --git a/core/sip/exclusive_file.cpp b/core/sip/exclusive_file.cpp
index 7712db67..8273989b 100644
--- a/core/sip/exclusive_file.cpp
+++ b/core/sip/exclusive_file.cpp
@@ -32,7 +32,7 @@ class _excl_file_reg
   
 public:
   exclusive_file* get(const string& name, bool& is_new) {
-    AmLock l(files_mut);
+    lock_guard<AmMutex> l(files_mut);
     map<string,excl_file_entry>::iterator it = files.find(name);
     if(it != files.end()) {
       excl_file_entry& fe = it->second;
@@ -62,7 +62,7 @@ public:
   }
 
   void deref(const string& name) {
-    AmLock l(files_mut);
+    lock_guard<AmMutex> l(files_mut);
     map<string,excl_file_entry>::iterator it = files.find(name);
     if(it != files.end()) {
       excl_file_entry& fe = it->second;
@@ -76,7 +76,7 @@ public:
   }
 
   bool delete_on_flushed(const string& name) {
-    AmLock l(files_mut);
+    lock_guard<AmMutex> l(files_mut);
     map<string,excl_file_entry>::iterator it = files.find(name);
     if(it != files.end()) {
       excl_file_entry& fe = it->second;
diff --git a/core/sip/msg_logger.cpp b/core/sip/msg_logger.cpp
index 0fb53474..27d67ad1 100644
--- a/core/sip/msg_logger.cpp
+++ b/core/sip/msg_logger.cpp
@@ -105,7 +105,7 @@ int cf_msg_logger::log(const char* buf, int len,
   string src = addr2str(src_ip);
   string dst = addr2str(dst_ip);
 
-  AmLock _l(*(AmMutex*)excl_fp);
+  lock_guard<exclusive_file> _l(*excl_fp);
 
   write_src_dst(src);
   write_src_dst(dst);
diff --git a/core/sip/tcp_trsp.cpp b/core/sip/tcp_trsp.cpp
index 82802f5f..0e206476 100644
--- a/core/sip/tcp_trsp.cpp
+++ b/core/sip/tcp_trsp.cpp
@@ -244,7 +244,7 @@ int tcp_trsp_socket::check_connection()
 int tcp_trsp_socket::send(const sockaddr_storage* sa, const char* msg, 
 			  const int msg_len, unsigned int flags)
 {
-  AmLock _l(sock_mut);
+  lock_guard<AmMutex> _l(sock_mut);
 
   if(closed || (check_connection() < 0))
     return -1;
@@ -309,7 +309,7 @@ void tcp_trsp_socket::on_read(short ev)
       return;
     }
 
-    AmLock _l(sock_mut);
+    lock_guard<AmMutex> _l(sock_mut);
     DBG("on_read (connected = %i)",connected);
 
     bytes = ::read(sd,get_input(),get_input_free_space());
@@ -426,7 +426,7 @@ int tcp_trsp_socket::parse_input()
 
 void tcp_trsp_socket::on_write(short ev)
 {
-  AmLock _l(sock_mut);
+  lock_guard<AmMutex> _l(sock_mut);
 
   DBG("on_write (connected = %i)",connected);
   if(!connected) {