diff --git a/simgear/math/SGMath.hxx b/simgear/math/SGMath.hxx
index e33fe3ac..fa4e69cd 100644
--- a/simgear/math/SGMath.hxx
+++ b/simgear/math/SGMath.hxx
@@ -21,6 +21,8 @@
 /// Just include them all
 
 #include <iosfwd>
+// FIXME, make it compile on IRIX
+#include <osg/GL>
 
 #include "SGMathFwd.hxx"