diff --git a/CMakeLists.txt b/CMakeLists.txt
index f24abbbeb..e7d65cf5b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -907,6 +907,7 @@ message (STATUS "hamlib_LIBRARY_DIRS: ${hamlib_LIBRARY_DIRS}")
 
 set (CMAKE_REQUIRED_INCLUDES "${hamlib_INCLUDE_DIRS}")
 set (CMAKE_REQUIRED_LIBRARIES "${hamlib_LIBRARIES}")
+check_symbol_exists (CACHE_ALL "hamlib/rig.h" HAVE_HAMLIB_OLD_CACHING)
 check_symbol_exists (rig_set_cache_timeout_ms "hamlib/rig.h" HAVE_HAMLIB_CACHING)
 
 
diff --git a/Darwin/sysctl.conf b/Darwin/sysctl.conf
index 830bba803..4d6cf69e0 100644
--- a/Darwin/sysctl.conf
+++ b/Darwin/sysctl.conf
@@ -1,6 +1,5 @@
-kern.sysv.shmmax=14680064
+kern.sysv.shmmax=104857600
 kern.sysv.shmmin=1
 kern.sysv.shmmni=128
 kern.sysv.shmseg=32
-kern.sysv.shmall=17920
-
+kern.sysv.shmall=25600
diff --git a/Network/PSKReporter.cpp b/Network/PSKReporter.cpp
index fcdebf2c5..8c8d7948d 100644
--- a/Network/PSKReporter.cpp
+++ b/Network/PSKReporter.cpp
@@ -145,8 +145,10 @@ public:
 
 #if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
     connect (socket_.get (), &QAbstractSocket::errorOccurred, this, &PSKReporter::impl::handle_socket_error);
-#else
+#elif QT_VERSION >= QT_VERSION_CHECK(5, 7, 0)
     connect (socket_.data (), QOverload<QAbstractSocket::SocketError>::of (&QAbstractSocket::error), this, &PSKReporter::impl::handle_socket_error);
+#else
+    connect (socket_.data (), static_cast<void (QAbstractSocket::*) (QAbstractSocket::SocketError)> (&QAbstractSocket::error), this, &PSKReporter::impl::handle_socket_error);
 #endif
 
     // use this for pseudo connection with UDP, allows us to use
diff --git a/Transceiver/HamlibTransceiver.cpp b/Transceiver/HamlibTransceiver.cpp
index 3923f4c5d..ce7408a04 100644
--- a/Transceiver/HamlibTransceiver.cpp
+++ b/Transceiver/HamlibTransceiver.cpp
@@ -14,6 +14,10 @@
 
 #include "moc_HamlibTransceiver.cpp"
 
+#if HAVE_HAMLIB_OLD_CACHING
+#define HAMLIB_CACHE_ALL CACHE_ALL
+#endif
+
 namespace
 {
   // Unfortunately bandwidth is conflated  with mode, this is probably
@@ -606,7 +610,7 @@ int HamlibTransceiver::do_start ()
         }
     }
 
-#if HAVE_HAMLIB_CACHING
+#if HAVE_HAMLIB_CACHING || HAVE_HAMLIB_OLD_CACHING
   // we must disable Hamlib caching because it lies about frequency
   // for less than 1 Hz resolution rigs
   auto orig_cache_timeout = rig_get_cache_timeout_ms (rig_.data (), HAMLIB_CACHE_ALL);
@@ -653,7 +657,7 @@ int HamlibTransceiver::do_start ()
       resolution = -1;          // best guess
     }
 
-#if HAVE_HAMLIB_CACHING
+#if HAVE_HAMLIB_CACHING || HAVE_HAMLIB_OLD_CACHING
   // revert Hamlib cache timeout
   rig_set_cache_timeout_ms (rig_.data (), HAMLIB_CACHE_ALL, orig_cache_timeout);
 #endif
diff --git a/widgets/mainwindow.cpp b/widgets/mainwindow.cpp
index 372e74bc5..9fb3341d1 100644
--- a/widgets/mainwindow.cpp
+++ b/widgets/mainwindow.cpp
@@ -3019,34 +3019,19 @@ void MainWindow::decode()                                       //decode()
   if( m_diskData ) {
     dec_data.params.lapcqonly=false;
   }
-  m_msec0=QDateTime::currentMSecsSinceEpoch();
   if(!m_dataAvailable or m_TRperiod==0.0) return;
   ui->DecodeButton->setChecked (true);
-  if(!dec_data.params.nagain && m_diskData && (m_TRperiod >= 60.0)) {
+  if(!dec_data.params.nagain && m_diskData && m_TRperiod >= 60.) {
     dec_data.params.nutc=dec_data.params.nutc/100;
   }
   if(dec_data.params.nagain==0 && dec_data.params.newdat==1 && (!m_diskData)) {
-    qint64 nperiods=now.toMSecsSinceEpoch()/(1000.0*m_TRperiod);
-    m_dateTimeSeqStart=QDateTime::fromMSecsSinceEpoch(qint64(1000.0*nperiods*m_TRperiod)).toUTC();
-    qint64 ms = QDateTime::currentMSecsSinceEpoch() % 86400000;
-    int imin=ms/60000;
-    int ihr=imin/60;
-    imin=imin % 60;
-    if(m_TRperiod>=60) imin=imin - (imin % (int(m_TRperiod)/60));
-    dec_data.params.nutc=100*ihr + imin;
-    if(m_TRperiod < 60) {
-      qint64 ms=1000.0*(2.0-m_TRperiod);
-      if(m_mode=="FST4") ms=1000.0*(6.0-m_TRperiod);
-      //Adjust for FT8 early decode:
-      if(m_mode=="FT8" and m_ihsym==m_earlyDecode and !m_diskData) ms+=(m_hsymStop-m_earlyDecode)*288;
-      if(m_mode=="FT8" and m_ihsym==m_earlyDecode2 and !m_diskData) ms+=(m_hsymStop-m_earlyDecode2)*288;
-      QDateTime t=QDateTime::currentDateTimeUtc().addMSecs(ms);
-      ihr=t.toString("hh").toInt();
-      imin=t.toString("mm").toInt();
-      int isec=t.toString("ss").toInt();
-      isec=isec - fmod(double(isec),m_TRperiod);
-      dec_data.params.nutc=10000*ihr + 100*imin + isec;
-    }
+    auto t_start = qt_truncate_date_time_to (QDateTime::currentDateTimeUtc (), m_TRperiod * 1.e3);
+    auto t = t_start.time ();
+    dec_data.params.nutc = t.hour () * 100 + t.minute ();
+    if (m_TRperiod < 60.)
+      {
+        dec_data.params.nutc = dec_data.params.nutc * 100 + t.second ();
+      }
   }
 
   if(m_nPick==1 and !m_diskData) {
diff --git a/widgets/mainwindow.h b/widgets/mainwindow.h
index 071ffd90d..8c19c8302 100644
--- a/widgets/mainwindow.h
+++ b/widgets/mainwindow.h
@@ -401,7 +401,6 @@ private:
   qint64  m_msErase;
   qint64  m_secBandChanged;
   qint64  m_freqMoon;
-  qint64  m_msec0;
   qint64  m_fullFoxCallTime;
 
   Frequency m_freqNominal;
diff --git a/wsjtx_config.h.in b/wsjtx_config.h.in
index 0866cf061..7da6a4cdd 100644
--- a/wsjtx_config.h.in
+++ b/wsjtx_config.h.in
@@ -19,6 +19,7 @@ extern "C"  {
 #cmakedefine PROJECT_SAMPLES_URL "@PROJECT_SAMPLES_URL@"
 #cmakedefine PROJECT_SUMMARY_DESCRIPTION "@PROJECT_SUMMARY_DESCRIPTION@"
 
+#cmakedefine01 HAVE_HAMLIB_OLD_CACHING
 #cmakedefine01 HAVE_HAMLIB_CACHING
 
 #cmakedefine01 WSJT_SHARED_RUNTIME