--- a/water_cmd.c	Fri Jun 02 21:03:59 2006 +0000
+++ b/water_cmd.c	Sat Jun 03 12:53:29 2006 +0000
@@ -141,7 +141,11 @@
 		return_cmd_error(STR_1000_LAND_SLOPED_IN_WRONG_DIRECTION);
 	}
 
-	if (IsBridgeAbove(tile) || IsBridgeAbove(tile - delta) || IsBridgeAbove(tile + delta)) return_cmd_error(STR_5007_MUST_DEMOLISH_BRIDGE_FIRST);
+	if ((MayHaveBridgeAbove(tile) && IsBridgeAbove(tile)) ||
+	    (MayHaveBridgeAbove(tile - delta) && IsBridgeAbove(tile - delta)) ||
+	    (MayHaveBridgeAbove(tile + delta) && IsBridgeAbove(tile + delta))) {
+		return_cmd_error(STR_5007_MUST_DEMOLISH_BRIDGE_FIRST);
+	}
 
 	if (flags & DC_EXEC) {
 		MakeLock(tile, dir);