diff --git a/simgear/scene/sky/bbcache.cxx b/simgear/scene/sky/bbcache.cxx
index ad253cda..a05ce7c8 100644
--- a/simgear/scene/sky/bbcache.cxx
+++ b/simgear/scene/sky/bbcache.cxx
@@ -30,7 +30,7 @@
 #include <plib/ssg.h>
 #include <simgear/screen/extensions.hxx>
 #include <simgear/screen/RenderTexture.h>
-#include SG_GLUT_H
+#include SG_GLU_H
 
 #include "bbcache.hxx"
 
diff --git a/simgear/scene/sky/cloudfield.cxx b/simgear/scene/sky/cloudfield.cxx
index a847c57a..83f941d6 100644
--- a/simgear/scene/sky/cloudfield.cxx
+++ b/simgear/scene/sky/cloudfield.cxx
@@ -31,7 +31,6 @@
 #include <simgear/math/sg_geodesy.hxx>
 
 #include STL_ALGORITHM
-#include SG_GLUT_H
 #include <vector>
 
 SG_USING_STD(vector);
diff --git a/simgear/scene/sky/newcloud.cxx b/simgear/scene/sky/newcloud.cxx
index f49b7df5..e0bcfce7 100644
--- a/simgear/scene/sky/newcloud.cxx
+++ b/simgear/scene/sky/newcloud.cxx
@@ -31,7 +31,7 @@
 #include <simgear/misc/sg_path.hxx>
 
 #include STL_ALGORITHM
-#include SG_GLUT_H
+#include SG_GLU_H
 
 #include "newcloud.hxx"