diff --git a/simgear/scene/material/matmodel.cxx b/simgear/scene/material/matmodel.cxx
index d8c9e3f1..bdad512e 100644
--- a/simgear/scene/material/matmodel.cxx
+++ b/simgear/scene/material/matmodel.cxx
@@ -37,6 +37,7 @@ using std::map;
 #include <osg/Transform>
 
 #include <simgear/debug/logstream.hxx>
+#include <simgear/math/SGMath.hxx>
 #include <simgear/math/sg_random.h>
 #include <simgear/misc/sg_path.hxx>
 #include <simgear/misc/sgstream.hxx>
diff --git a/simgear/scene/model/model.cxx b/simgear/scene/model/model.cxx
index 54e74924..d41529ad 100644
--- a/simgear/scene/model/model.cxx
+++ b/simgear/scene/model/model.cxx
@@ -11,6 +11,7 @@
 #include <osgDB/ReadFile>
 #include <osgDB/SharedStateManager>
 
+#include <simgear/math/SGMath.hxx>
 #include <simgear/scene/util/SGSceneFeatures.hxx>
 
 #include <simgear/structure/exception.hxx>