diff --git a/Fltk/openglWindow.cpp b/Fltk/openglWindow.cpp
index 2a4b44d15824a767ba9c54d0437c6b39b6f82902..20abdac759b6daf5c6387d36010571ddc16c2da4 100644
--- a/Fltk/openglWindow.cpp
+++ b/Fltk/openglWindow.cpp
@@ -15,7 +15,11 @@
 #include "MElement.h"
 #include "Numeric.h"
 #include "FlGui.h"
+#if defined(__APPLE__)
+#include <OpenGL/glu.h>
+#else
 #include <GL/glu.h>
+#endif
 #include "Context.h"
  
 static void lassoZoom(drawContext *ctx, mousePosition &click1, mousePosition &click2)