diff --git a/CMakeLists.txt b/CMakeLists.txt
index 046a26fc0..3dc5b0823 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1437,7 +1437,7 @@ else ()
     )
   if (WIN32)
     set_target_properties (wsjtx PROPERTIES
-      LINK_FLAGS -Wl,--stack,0x400000,--heap,0x20000000
+      LINK_FLAGS -Wl,--stack,0x1000000,--heap,0x20000000
       )
   endif ()
 endif ()
diff --git a/widgets/mainwindow.cpp b/widgets/mainwindow.cpp
index 1486db3e9..d20331bc4 100644
--- a/widgets/mainwindow.cpp
+++ b/widgets/mainwindow.cpp
@@ -9117,15 +9117,15 @@ void MainWindow::write_all(QString txRx, QString message)
   QString msg;
   QString mode_string;
 
-  if (message[4]==' ') {
+  if (message.size () > 5 && message[4]==' ') {
      msg=message.mid(4,-1);
   } else {
      msg=message.mid(6,-1);
   }
 
-  if (message[19]=='#') {
+  if (message.size () > 19 && message[19]=='#') {
      mode_string="JT65  ";
-  } else if (message[19]=='@') {
+  } else if (message.size () > 19 && message[19]=='@') {
      mode_string="JT9   ";
   } else {
      mode_string=m_mode.leftJustified(6,' ');