diff -r 9062c6cc760b -r 5d93386b748b src/town_cmd.cpp
--- a/src/town_cmd.cpp	Sun Aug 26 21:53:11 2007 +0000
+++ b/src/town_cmd.cpp	Mon Aug 27 21:18:04 2007 +0000
@@ -706,6 +706,7 @@
 					res = DoCommand(tile, slope, 0, DC_EXEC | DC_AUTO | DC_NO_WATER,
 					                      CMD_TERRAFORM_LAND);
 				} else {
+					/* Note: Do not replace " ^ 0xF" with ComplementSlope(). The slope might be steep. */
 					res = DoCommand(tile, slope ^ 0xF, 1, DC_EXEC | DC_AUTO | DC_NO_WATER,
 					                      CMD_TERRAFORM_LAND);
 				}