diff --git a/simgear/scene/util/SGReaderWriterOptions.cxx b/simgear/scene/util/SGReaderWriterOptions.cxx
index d2951cc5..12e32128 100644
--- a/simgear/scene/util/SGReaderWriterOptions.cxx
+++ b/simgear/scene/util/SGReaderWriterOptions.cxx
@@ -17,6 +17,12 @@
 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 //
 
+#ifdef HAVE_CONFIG_H
+#  include <simgear_config.h>
+#endif
+
+#include <simgear/scene/util/OsgMath.hxx>
+
 #include "SGReaderWriterOptions.hxx"
 
 #include <osgDB/Registry>