diff --git a/include/GL/glu.h b/include/GL/glu.h
index cd967ac5ed4..ba2228d8d86 100644
--- a/include/GL/glu.h
+++ b/include/GL/glu.h
@@ -284,7 +284,7 @@ typedef GLUtesselator GLUtriangulatorObj;
 #define GLU_TESS_MAX_COORD 1.0e150
 
 /* Internal convenience typedefs */
-typedef void (GLAPIENTRYP _GLUfuncptr)();
+typedef void (GLAPIENTRYP _GLUfuncptr)(void);
 
 GLAPI void GLAPIENTRY gluBeginCurve (GLUnurbs* nurb);
 GLAPI void GLAPIENTRY gluBeginPolygon (GLUtesselator* tess);