diff --git a/simgear/route/route.cxx b/simgear/route/route.cxx
index 431ceea1..b3b0dfb7 100644
--- a/simgear/route/route.cxx
+++ b/simgear/route/route.cxx
@@ -20,6 +20,9 @@
 //
 // $Id$
 
+#ifdef HAVE_CONFIG_H
+#  include <simgear_config.h>
+#endif
 
 #include <plib/sg.h>