diff --git a/src/Sound/beacon.cxx b/src/Sound/beacon.cxx
index 0ce8fb90c..41a990271 100644
--- a/src/Sound/beacon.cxx
+++ b/src/Sound/beacon.cxx
@@ -24,6 +24,7 @@
 #include "beacon.hxx"
 
 #include <simgear/structure/exception.hxx>
+#include <Main/fg_props.hxx>
 #include <Main/globals.hxx>
 
 // constructor
diff --git a/src/Sound/morse.cxx b/src/Sound/morse.cxx
index 2d21be642..754c98eb3 100644
--- a/src/Sound/morse.cxx
+++ b/src/Sound/morse.cxx
@@ -23,6 +23,7 @@
 
 #include <simgear/constants.h>
 
+#include <Main/fg_props.hxx>
 #include <Main/globals.hxx>
 
 #include "morse.hxx"