diff --git a/gl_util.h b/gl_util.h
index b0f2e33..c8504e5 100644
--- a/gl_util.h
+++ b/gl_util.h
@@ -8,12 +8,14 @@
 /* Include prototype flag */
 #if (defined(_WIN32) || defined(HAVE_W32API))
 #define GL_GLEXT_PROCS
-#else
+#elif !defined(HAVE_AGL_GLUT)
 #define GL_GLEXT_PROTOTYPES
 #endif
 
 /* Provide GL header files for Windows and Apple */
-#define INCLUDE_LOCAL_HEADER defined(HAVE_W32API) || defined(__APPLE__)
+#if defined(HAVE_W32API) || defined(__APPLE__)
+#define INCLUDE_LOCAL_HEADER 1
+#endif
 #if INCLUDE_LOCAL_HEADER
 #include "./include/GL/gl.h"
 #else
diff --git a/glext_procs.h b/glext_procs.h
index 16036fa..9426cf0 100644
--- a/glext_procs.h
+++ b/glext_procs.h
@@ -1,3 +1,5 @@
+
+#ifndef HAVE_AGL_GLUT
 #ifndef __glext_procs_h_
 #define __glext_procs_h_
 
@@ -16244,3 +16246,5 @@ static PFNGLREPLACEMENTCODEUITEXCOORD2FCOLOR4FNORMAL3FVERTEX3FVSUNPROC glReplace
 #endif
 
 #endif
+
+#endif  /* HAVE_AGL_GLUT */
diff --git a/utils/glext_procs.pl b/utils/glext_procs.pl
index 426d99f..5fd4adb 100755
--- a/utils/glext_procs.pl
+++ b/utils/glext_procs.pl
@@ -25,6 +25,8 @@
 }
 close(EXPS);
 
+print EXTS "\n#ifndef HAVE_AGL_GLUT\n";
+
 # Header
 my $header = qq
 {#ifndef %s
@@ -188,5 +190,7 @@
   }
 }
 
+print EXTS "\n#endif  /* HAVE_AGL_GLUT */\n";
+
 close(EXTS);
 close(FILE);