diff --git a/src/viewport.cpp b/src/viewport.cpp
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -1356,9 +1356,6 @@ static void ViewportAddKdtreeSigns(DrawP
 	bool show_signs = HasBit(_display_opt, DO_SHOW_SIGNS) && !IsInvisibilitySet(TO_SIGNS);
 	bool show_competitors = HasBit(_display_opt, DO_SHOW_COMPETITOR_SIGNS);
 
-	const BaseStation *st;
-	const Sign *si;
-
 	/* Collect all the items first and draw afterwards, to ensure layering */
 	std::vector<const BaseStation *> stations;
 	std::vector<const Town *> towns;
@@ -1366,34 +1363,36 @@ static void ViewportAddKdtreeSigns(DrawP
 
 	_viewport_sign_kdtree.FindContained(search_rect.left, search_rect.top, search_rect.right, search_rect.bottom, [&](const ViewportSignKdtreeItem & item) {
 		switch (item.type) {
-			case ViewportSignKdtreeItem::VKI_STATION:
+			case ViewportSignKdtreeItem::VKI_STATION: {
 				if (!show_stations) break;
-				st = BaseStation::Get(item.id.station);
+				const BaseStation *st = BaseStation::Get(item.id.station);
 
 				/* Don't draw if station is owned by another company and competitor station names are hidden. Stations owned by none are never ignored. */
 				if (!show_competitors && _local_company != st->owner && st->owner != OWNER_NONE) break;
 
 				stations.push_back(st);
 				break;
-
-			case ViewportSignKdtreeItem::VKI_WAYPOINT:
+			}
+
+			case ViewportSignKdtreeItem::VKI_WAYPOINT: {
 				if (!show_waypoints) break;
-				st = BaseStation::Get(item.id.station);
+				const BaseStation *st = BaseStation::Get(item.id.station);
 
 				/* Don't draw if station is owned by another company and competitor station names are hidden. Stations owned by none are never ignored. */
 				if (!show_competitors && _local_company != st->owner && st->owner != OWNER_NONE) break;
 
 				stations.push_back(st);
 				break;
+			}
 
 			case ViewportSignKdtreeItem::VKI_TOWN:
 				if (!show_towns) break;
 				towns.push_back(Town::Get(item.id.town));
 				break;
 
-			case ViewportSignKdtreeItem::VKI_SIGN:
+			case ViewportSignKdtreeItem::VKI_SIGN: {
 				if (!show_signs) break;
-				si = Sign::Get(item.id.sign);
+				const Sign *si = Sign::Get(item.id.sign);
 
 				/* Don't draw if sign is owned by another company and competitor signs should be hidden.
 				* Note: It is intentional that also signs owned by OWNER_NONE are hidden. Bankrupt
@@ -1402,6 +1401,7 @@ static void ViewportAddKdtreeSigns(DrawP
 
 				signs.push_back(si);
 				break;
+			}
 
 			default:
 				NOT_REACHED();