diff --git a/include/SDL_opengl_glext.h b/include/SDL_opengl_glext.h
index 8527e1744..bdd3efb79 100644
--- a/include/SDL_opengl_glext.h
+++ b/include/SDL_opengl_glext.h
@@ -1,4 +1,5 @@
-#ifndef __gl_glext_h_
+#if !defined(__glext_h_) && !defined(__gl_glext_h_)
+#define __glext_h_ 1
 #define __gl_glext_h_ 1
 
 #ifdef __cplusplus