diff --git a/src/GUI/AirportList.hxx b/src/GUI/AirportList.hxx
index 99d131f56..7a3cfaef8 100644
--- a/src/GUI/AirportList.hxx
+++ b/src/GUI/AirportList.hxx
@@ -1,10 +1,20 @@
 // AirportList.hxx - scrolling list of airports.
 
-#ifndef __AIRPORTLIST_HXX
-#define __AIRPORTLIST_HXX
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#pragma once
 
 #include <simgear/compiler.h>
+
+// ensure we include this before puAux.h, so that 
+// #define _PU_H_ 1 has been done, and hence we don't
+// include the un-modified system pu.h
+#include "FlightGear_pu.h"
+
 #include <plib/puAux.h>
+
 #include "FGPUIDialog.hxx"
 
 class FGAirportList;
@@ -23,4 +33,3 @@ private:
     std::string _filter;
 };
 
-#endif // __AIRPORTLIST_HXX
diff --git a/src/GUI/FGPUIDialog.hxx b/src/GUI/FGPUIDialog.hxx
index de342397d..30b274254 100644
--- a/src/GUI/FGPUIDialog.hxx
+++ b/src/GUI/FGPUIDialog.hxx
@@ -1,9 +1,18 @@
 // FGPUIDialog.hxx - XML-configured dialog box.
+/*
+ * SPDX-FileCopyrightText: 2012 (C) James Turner <james@flightgear.org>
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
 
 #pragma once
 
 #include "dialog.hxx"
 
+// ensure we include this before puAux.h, so that 
+// #define _PU_H_ 1 has been done, and hence we don't
+// include the un-modified system pu.h
+#include "FlightGear_pu.h"
+
 #include <plib/puAux.h>
 
 #include <simgear/misc/sg_path.hxx>
diff --git a/src/GUI/FlightGear_pu.h b/src/GUI/FlightGear_pu.h
index 08a9e9bbd..35c3fc1c0 100644
--- a/src/GUI/FlightGear_pu.h
+++ b/src/GUI/FlightGear_pu.h
@@ -377,6 +377,10 @@ protected:
   int *   getIntegerp ( void ) { return res_integer != NULL ? res_integer : &integer ; }
   float * getFloaterp ( void ) { return res_floater != NULL ? res_floater : &floater ; }
   char *  getStringp  ( void ) { return res_string != NULL ? res_string : string ; }
+
+  // added by James to allow sprintf -> snprintf migration
+  int     getStringLength()    { return res_string != NULL ? res_string_sz : string_size ;}
+
   bool *  getBooleanp ( void ) { return res_bool != NULL ? res_bool : &boolean ; }
 
   void enableConversion  ( void ) { convert = TRUE  ; }
@@ -468,7 +472,9 @@ public:
 
     if ( convert == TRUE )
     {
-      *getFloaterp () = (float) i ; sprintf ( getStringp (), "%d", i ) ; *getBooleanp () = ( i != 0 ) ;
+      *getFloaterp () = (float) i ; 
+      snprintf ( getStringp (), getStringLength(), "%d", i ) ; 
+      *getBooleanp () = ( i != 0 ) ;
     }
 
     puPostRefresh () ;
@@ -480,7 +486,9 @@ public:
 
     if ( convert == TRUE )
     {
-      *getIntegerp () = (int) f ; sprintf ( getStringp (), "%g", f ) ; *getBooleanp () = ( f != 0.0 ) ;
+      *getIntegerp () = (int) f ; 
+      snprintf ( getStringp (), getStringLength(), "%g", f ) ; 
+      *getBooleanp () = ( f != 0.0 ) ;
     }
 
     puPostRefresh () ;
@@ -494,7 +502,9 @@ public:
 
     if ( convert == TRUE )
     {
-      *getIntegerp () = b ? 1 : 0 ; *getFloaterp () = b ? 1.0f : 0.0f ; sprintf ( getStringp (), "%s", b ? "1" : "0" ) ;
+      *getIntegerp () = b ? 1 : 0 ; 
+      *getFloaterp () = b ? 1.0f : 0.0f ; 
+      snprintf ( getStringp (), getStringLength(), "%s", b ? "1" : "0" ) ;
     }
 
     puPostRefresh () ;
diff --git a/src/GUI/MapWidget.cxx b/src/GUI/MapWidget.cxx
index 0472950e2..3b195c7ea 100644
--- a/src/GUI/MapWidget.cxx
+++ b/src/GUI/MapWidget.cxx
@@ -1,11 +1,20 @@
-#ifdef HAVE_CONFIG_H
-#  include "config.h"
-#endif
+/*
+ * SPDX-FileCopyrightText: (C) 2010 James Turner <james@flightgear.org>
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "config.h"
 
 #include "MapWidget.hxx"
 
 #include <sstream>
 #include <algorithm> // for std::sort
+
+// ensure we include this before puAux.h, so that 
+// #define _PU_H_ 1 has been done, and hence we don't
+// include the un-modified system pu.h
+#include "FlightGear_pu.h"
+
 #include <plib/puAux.h>
 
 #include <simgear/sg_inlines.h>
diff --git a/src/GUI/MapWidget.hxx b/src/GUI/MapWidget.hxx
index 03728c4e6..84764a513 100644
--- a/src/GUI/MapWidget.hxx
+++ b/src/GUI/MapWidget.hxx
@@ -1,5 +1,9 @@
-#ifndef GUI_MAPWIDGET_HXX
-#define GUI_MAPWIDGET_HXX
+/*
+ * SPDX-FileCopyrightText: (C) 2010 James Turner <james@flightgear.org>
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#pragma once
 
 #include <map>
 #include <simgear/compiler.h>
@@ -158,5 +162,3 @@ private:
   double _gridSpacing;
   SGGeod _gridCenter;
 };
-
-#endif // of GUI_MAPWIDGET_HXX
diff --git a/src/GUI/new_gui.cxx b/src/GUI/new_gui.cxx
index f1015a2aa..fb7724972 100644
--- a/src/GUI/new_gui.cxx
+++ b/src/GUI/new_gui.cxx
@@ -1,5 +1,9 @@
 // new_gui.cxx: implementation of XML-configurable GUI support.
 
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
 #include <config.h>
 
 #include "new_gui.hxx"
@@ -35,6 +39,11 @@
 #endif
 
 #if defined(HAVE_PUI)
+    // ensure we include this before puAux.h, so that 
+    // #define _PU_H_ 1 has been done, and hence we don't
+    // include the un-modified system pu.h
+    #include "FlightGear_pu.h"
+
     #include <plib/puAux.h>
 #endif
 
diff --git a/src/GUI/property_list.hxx b/src/GUI/property_list.hxx
index 8e1780fb2..0aa5cec35 100644
--- a/src/GUI/property_list.hxx
+++ b/src/GUI/property_list.hxx
@@ -25,6 +25,11 @@
 
 #include <string>
 
+// ensure we include this before puAux.h, so that 
+// #define _PU_H_ 1 has been done, and hence we don't
+// include the un-modified system pu.h
+#include "FlightGear_pu.h"
+
 #include <plib/puAux.h>
 #include <simgear/props/props.hxx>
 #include "FGPUIDialog.hxx"