diff --git a/src/viewport.cpp b/src/viewport.cpp
index f1080408c3..1f40ff8e71 100644
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -1759,10 +1759,10 @@ void ViewportSign::MarkDirty(ZoomLevel maxzoom) const
 	Rect zoomlevels[ZOOM_LVL_COUNT];
 
 	for (ZoomLevel zoom = ZOOM_LVL_BEGIN; zoom != ZOOM_LVL_END; zoom++) {
-		/* FIXME: This doesn't switch to width_small when appropriate. */
-		zoomlevels[zoom].left   = this->center - ScaleByZoom(this->width_normal / 2 + 1, zoom);
+		const int width = zoom >= ZOOM_LVL_OUT_16X ? this->width_small : this->width_normal ;
+		zoomlevels[zoom].left   = this->center - ScaleByZoom(width / 2 + 1, zoom);
 		zoomlevels[zoom].top    = this->top    - ScaleByZoom(1, zoom);
-		zoomlevels[zoom].right  = this->center + ScaleByZoom(this->width_normal / 2 + 1, zoom);
+		zoomlevels[zoom].right  = this->center + ScaleByZoom(width / 2 + 1, zoom);
 		zoomlevels[zoom].bottom = this->top    + ScaleByZoom(VPSM_TOP + FONT_HEIGHT_NORMAL + VPSM_BOTTOM + 1, zoom);
 	}