diff --git a/tunnelbridge_cmd.c b/tunnelbridge_cmd.c
--- a/tunnelbridge_cmd.c
+++ b/tunnelbridge_cmd.c
@@ -716,7 +716,7 @@ static int32 ClearTile_TunnelBridge(Tile
 	return CMD_ERROR;
 }
 
-int32 DoConvertTunnelBridgeRail(TileIndex tile, uint totype, bool exec)
+int32 DoConvertTunnelBridgeRail(TileIndex tile, RailType totype, bool exec)
 {
 	TileIndex endtile;
 	uint length;