diff --git a/hw/xfree86/modes/xf86RandR12.c b/hw/xfree86/modes/xf86RandR12.c
index 1dca223fe..4767f2671 100644
--- a/hw/xfree86/modes/xf86RandR12.c
+++ b/hw/xfree86/modes/xf86RandR12.c
@@ -743,6 +743,9 @@ xf86RandR12CrtcSet (ScreenPtr	pScreen,
     xf86CrtcPtr		*save_crtcs;
     Bool		save_enabled = crtc->enabled;
 
+    if (!crtc->scrn->vtSema)
+	return FALSE;
+
     save_crtcs = xalloc(config->num_output * sizeof (xf86CrtcPtr));
     if ((randr_mode != NULL) != crtc->enabled)
 	changed = TRUE;