diff --git a/include/osg/Texture b/include/osg/Texture
index 3880ee1ef..b0478b2ea 100644
--- a/include/osg/Texture
+++ b/include/osg/Texture
@@ -179,7 +179,11 @@
 
 #ifndef GL_TEXTURE_COMPARE_MODE_ARB
     #define GL_TEXTURE_COMPARE_MODE_ARB       0x884C
+#endif
+#ifndef GL_TEXTURE_COMPARE_FUNC_ARB
     #define GL_TEXTURE_COMPARE_FUNC_ARB       0x884D
+#endif
+#ifndef GL_COMPARE_R_TO_TEXTURE_ARB
     #define GL_COMPARE_R_TO_TEXTURE_ARB       0x884E
 #endif