diff --git a/src/glu/sgi/include/gluos.h b/src/glu/sgi/include/gluos.h
index ac0a7874cec..290a06f0282 100644
--- a/src/glu/sgi/include/gluos.h
+++ b/src/glu/sgi/include/gluos.h
@@ -40,7 +40,13 @@
 #define NOIME
 #define NOMINMAX
 
+#ifdef __MINGW64_VERSION_MAJOR
+  #undef _WIN32_WINNT
+#endif
+
 #ifndef _WIN32_WINNT
+  /* XXX: Workaround a bug in mingw-w64's headers when NOGDI is set and
+   * _WIN32_WINNT >= 0x0600 */
   #define _WIN32_WINNT 0x0400
 #endif
 #ifndef STRICT