diff --git a/src/gfxinit.cpp b/src/gfxinit.cpp
--- a/src/gfxinit.cpp
+++ b/src/gfxinit.cpp
@@ -333,6 +333,7 @@ static const SpriteID _openttd_grf_index
 	377, 377, // · small
 	153, 153, // · medium
 	601, 601, // · large
+	SPR_WARNING_SIGN, SPR_WARNING_SIGN,
 	END
 };