diff --git a/src/newgrf_roadstop.cpp b/src/newgrf_roadstop.cpp
--- a/src/newgrf_roadstop.cpp
+++ b/src/newgrf_roadstop.cpp
@@ -157,7 +157,7 @@ uint32 RoadStopScopeResolver::GetVariabl
 
 			if (IsCustomRoadStopSpecIndex(nearby_tile)) {
 				const RoadStopSpecList ssl = BaseStation::GetByTile(nearby_tile)->roadstop_speclist[GetCustomRoadStopSpecIndex(nearby_tile)];
-				res |= 1 << (ssl.grfid != grfid ? 9 : 8) | std::max<uint16_t>(ssl.localidx, 0xFF);
+				res |= 1 << (ssl.grfid != grfid ? 9 : 8) | ClampTo<uint8_t>(ssl.localidx);
 			}
 			return res;
 		}