diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
index d15a4ec64e..1287eac16b 100644
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -888,10 +888,11 @@ static CommandCost CmdRailTrackHelper(DoCommandFlags flags, TileIndex tile, Tile
 	CommandCost last_error = CMD_ERROR;
 	for (;;) {
 		ret = remove ? Command<CMD_REMOVE_SINGLE_RAIL>::Do(flags, tile, TrackdirToTrack(trackdir)) : Command<CMD_BUILD_SINGLE_RAIL>::Do(flags, tile, railtype, TrackdirToTrack(trackdir), auto_remove_signals);
+		if (!remove && ret.Failed() && ret.GetErrorMessage() == STR_ERROR_ALREADY_BUILT) ret = CommandCost(); // Treat "already built" as success
 
 		if (ret.Failed()) {
 			last_error = std::move(ret);
-			if (last_error.GetErrorMessage() != STR_ERROR_ALREADY_BUILT && !remove) {
+			if (!remove) {
 				if (fail_on_obstacle) return last_error;
 				if (had_success) break; // Keep going if we haven't constructed any rail yet, skipping the start of the drag
 			}
diff --git a/src/road_cmd.cpp b/src/road_cmd.cpp
index 2ceeeebaf9..211186114c 100644
--- a/src/road_cmd.cpp
+++ b/src/road_cmd.cpp
@@ -1020,12 +1020,12 @@ CommandCost CmdBuildLongRoad(DoCommandFlags flags, TileIndex end_tile, TileIndex
 		}
 
 		CommandCost ret = Command<CMD_BUILD_ROAD>::Do(flags, tile, bits, rt, drd, TownID::Invalid());
+		if (ret.Failed() && ret.GetErrorMessage() == STR_ERROR_ALREADY_BUILT) ret = CommandCost(); // Treat "already built" as success
+
 		if (ret.Failed()) {
 			last_error = std::move(ret);
-			if (last_error.GetErrorMessage() != STR_ERROR_ALREADY_BUILT) {
-				if (is_ai) return last_error;
-				if (had_success) break; // Keep going if we haven't constructed any road yet, skipping the start of the drag
-			}
+			if (is_ai) return last_error;
+			if (had_success) break; // Keep going if we haven't constructed any road yet, skipping the start of the drag
 		} else {
 			had_success = true;
 			/* Only pay for the upgrade on one side of the bridges and tunnels */