diff --git a/hw/xfree86/modes/xf86Crtc.c b/hw/xfree86/modes/xf86Crtc.c
index 2080b23..f80be0d 100644
--- a/hw/xfree86/modes/xf86Crtc.c
+++ b/hw/xfree86/modes/xf86Crtc.c
@@ -1903,7 +1903,9 @@ bestModeForAspect(xf86CrtcConfigPtr config, Bool *enabled, float aspect)
     int o = -1, p;
     DisplayModePtr mode = NULL, test = NULL, match = NULL;
 
-    nextEnabledOutput(config, enabled, &o);
+    if (!nextEnabledOutput(config, enabled, &o))
+	return NULL;
+
     while ((mode = nextAspectMode(config->output[o], mode, aspect))) {
 	test = mode;
 	for (p = o; nextEnabledOutput(config, enabled, &p); ) {