diff --git a/glquake.h b/glquake.h
index e058e20..3dba09a 100644
--- a/glquake.h
+++ b/glquake.h
@@ -428,7 +428,9 @@ extern	const char *gl_extensions;
 void GL_Bind (int texnum);
 
 #ifndef _WIN32
-#define APIENTRY /* */
+#ifndef APIENTRY
+# define APIENTRY /* */
+#endif
 #endif
 
 #if !defined (__APPLE__) && !defined (MACOSX)