diff --git a/progs/xdemos/glxswapcontrol.c b/progs/xdemos/glxswapcontrol.c
index 6a9a852e688..98b3d1b58f1 100644
--- a/progs/xdemos/glxswapcontrol.c
+++ b/progs/xdemos/glxswapcontrol.c
@@ -576,7 +576,7 @@ event_loop(Display *dpy, Window win)
 static void
 show_refresh_rate( Display * dpy )
 {
-#ifdef GLX_OML_sync_control
+#if defined(GLX_OML_sync_control) && (__STDC_VERSION__ >= 199901L)
    PFNGLXGETMSCRATEOMLPROC  get_msc_rate;
    int32_t  n;
    int32_t  d;