diff --git a/src/map_func.h b/src/map_func.h
index 7d3e11cd80..afe853b551 100644
--- a/src/map_func.h
+++ b/src/map_func.h
@@ -363,18 +363,6 @@ public:
 	static IterateWrapper Iterate() { return IterateWrapper(); }
 };
 
-/**
- * An offset value between two tiles.
- *
- * This value is used for the difference between
- * two tiles. It can be added to a TileIndex to get
- * the resulting TileIndex of the start tile applied
- * with this saved difference.
- *
- * @see TileDiffXY(int, int)
- */
-typedef int32_t TileIndexDiff;
-
 /**
  * Returns the TileIndex of a coordinate.
  *