diff --git a/hw/xfree86/modes/xf86Crtc.c b/hw/xfree86/modes/xf86Crtc.c
index 5a71bcfea..733106c4f 100644
--- a/hw/xfree86/modes/xf86Crtc.c
+++ b/hw/xfree86/modes/xf86Crtc.c
@@ -1714,9 +1714,11 @@ xf86SetScrnInfoModes (ScrnInfoPtr scrn)
     /* Set scrn->modes to the mode list for the 'compat' output */
     scrn->modes = xf86DuplicateModes(scrn, output->probed_modes);
 
-    for (mode = scrn->modes; mode; mode = mode->next)
-	if (xf86ModesEqual (mode, &crtc->desiredMode))
-	    break;
+    if (crtc) {
+	for (mode = scrn->modes; mode; mode = mode->next)
+	    if (xf86ModesEqual (mode, &crtc->desiredMode))
+		break;
+    }
 
     if (scrn->modes != NULL) {
 	/* For some reason, scrn->modes is circular, unlike the other mode