diff --git a/src/visualinfo.c b/src/visualinfo.c
index ca2c585..93957fd 100644
--- a/src/visualinfo.c
+++ b/src/visualinfo.c
@@ -598,7 +598,7 @@ VisualInfo (GLContext* ctx)
 #elif defined(__APPLE__) && !defined(GLEW_APPLE_GLX)
 
 void
-VisualInfo (GLContext* ctx)
+VisualInfo (GLContext* __attribute__((__unused__)) ctx)
 {
 /*
   int attrib[] = { AGL_RGBA, AGL_NONE };