diff --git a/hw/xfree86/modes/xf86Crtc.c b/hw/xfree86/modes/xf86Crtc.c
index df47598aa..f072109de 100644
--- a/hw/xfree86/modes/xf86Crtc.c
+++ b/hw/xfree86/modes/xf86Crtc.c
@@ -1185,10 +1185,12 @@ xf86InitialOutputPositions (ScrnInfoPtr scrn, DisplayModePtr *modes)
 		    output->initial_x += xf86ModeWidth (modes[or], relative->initial_rotation);
 		    break;
 		case OPTION_ABOVE:
-		    output->initial_y -= xf86ModeHeight (modes[o], output->initial_rotation);
+		    if (modes[o])
+			output->initial_y -= xf86ModeHeight (modes[o], output->initial_rotation);
 		    break;
 		case OPTION_LEFT_OF:
-		    output->initial_x -= xf86ModeWidth (modes[o], output->initial_rotation);
+		    if (modes[o])
+			output->initial_x -= xf86ModeWidth (modes[o], output->initial_rotation);
 		    break;
 		default:
 		    break;