diff -u -r tworld-1.2.1/play.c tworld-1.2.1-oddfix/play.c
--- tworld-1.2.1/play.c	2004-10-21 08:58:13.000000000 +0100
+++ tworld-1.2.1-oddfix/play.c	2006-01-22 16:12:26.000000000 +0000
@@ -196,7 +196,7 @@
 	state.stepping = 0;
     n = (state.stepping + delta) % 8;
     if (state.ruleset == Ruleset_MS)
-	n &= ~4;
+	n &= 4;
     if (state.stepping != n)
 	return setstepping(n, display);
     return TRUE;