diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -2129,7 +2129,7 @@ static void DrawTrackBits(TileInfo *ti, 
  * The addtion of 2 per enum is necessary in order to "jump" over the
  * green state sprite, all signal sprites being in pair,
  * starting with the off-red state */
-enum {
+enum SignalOffsets {
 	SIGNAL_TO_SOUTHWEST =  0,
 	SIGNAL_TO_NORTHEAST =  2,
 	SIGNAL_TO_SOUTHEAST =  4,