diff -rupN vfrnav-20201231/src/prefs.cc vfrnav-20201231-new/src/prefs.cc
--- vfrnav-20201231/src/prefs.cc	2021-01-11 17:56:47.000000000 +0100
+++ vfrnav-20201231-new/src/prefs.cc	2021-05-10 11:59:33.809251994 +0200
@@ -33,7 +33,9 @@ extern "C" {
 
 #ifdef HAVE_GNOMEBT
 //#include <gnomebt-chooser.h>
+extern "C" {
 #include <bluetooth-chooser.h>
+}
 #endif
 
 PrefsWindow::PrefsWindow(BaseObjectType * castitem, const Glib::RefPtr< Builder > & refxml)