diff --git a/include/osg/AlphaFunc b/include/osg/AlphaFunc
index f63f50f1f..953586517 100644
--- a/include/osg/AlphaFunc
+++ b/include/osg/AlphaFunc
@@ -16,10 +16,6 @@
 
 #include <osg/StateAttribute>
 
-#ifndef GL_ALPHA_TEST
-    #define GL_ALPHA_TEST 0x0BC0
-#endif
-
 namespace osg {
 
 /** Encapsulates OpenGL glAlphaFunc.
diff --git a/include/osg/GLDefines b/include/osg/GLDefines
index b3b44cea0..f97dbfa5c 100644
--- a/include/osg/GLDefines
+++ b/include/osg/GLDefines
@@ -600,6 +600,10 @@ typedef char GLchar;
 #define GL_RASTERIZER_DISCARD           0x8C89
 #endif
 
+#ifndef GL_ALPHA_TEST
+    #define GL_ALPHA_TEST 0x0BC0
+#endif
+
 namespace osg
 {
     #ifndef GL_VERSION_3_2