diff --git a/simgear/screen/RenderTexture.h b/simgear/screen/RenderTexture.h
index 73057dbe..78d56f6f 100644
--- a/simgear/screen/RenderTexture.h
+++ b/simgear/screen/RenderTexture.h
@@ -54,6 +54,9 @@
 #  include <X11/Xlib.h>
 #endif
 #include SG_GL_H
+#if defined( __MACH__)
+#  include <OpenGL/CGLTypes.h>
+#endif
 #ifndef _WIN32
 #  include SG_GLX_H
 #endif