diff --git a/api/gutil.C b/api/gutil.C
index 898eb75b48..2c54e11b1d 100755
--- a/api/gutil.C
+++ b/api/gutil.C
@@ -34,6 +34,7 @@
 #ifdef unix
 #include <GL/gl.h>
 #include <GL/glu.h>
+#include <GL/glut.h>
 #endif
 
 #include "gutil.h"