diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 28ea3d260bea..2bb3bc2ce693 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2798,6 +2798,8 @@ static int drm_cvt_modes(struct drm_connector *connector,
 		case 0x0c:
 			width = height * 15 / 9;
 			break;
+		default:
+			unreachable();
 		}
 
 		for (j = 1; j < 5; j++) {