diff --git a/Build.sh b/Build.sh
index 9eadfc0..31c559d 100644
--- a/Build.sh
+++ b/Build.sh
@@ -1,5 +1,5 @@
 #!/bin/sh
-srcversion='$MirOS: src/bin/mksh/Build.sh,v 1.621 2013/02/18 22:55:35 tg Exp $'
+srcversion='$MirOS: src/bin/mksh/Build.sh,v 1.622 2013/02/19 18:45:15 tg Exp $'
 #-
 # Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
 #		2011, 2012, 2013
@@ -1388,6 +1388,9 @@ ac_ifcpp 'ifdef MKSH_CONSERVATIVE_FDS' isset_MKSH_CONSERVATIVE_FDS '' \
 #ac_ifcpp 'ifdef MKSH_DISABLE_EXPERIMENTAL' isset_MKSH_DISABLE_EXPERIMENTAL '' \
 #    "if experimental features are to be omitted" && \
 #    check_categories="$check_categories noexperimental"
+ac_ifcpp 'ifdef MKSH_MIDNIGHTBSD01ASH_COMPAT' isset_MKSH_MIDNIGHTBSD01ASH_COMPAT '' \
+    'if the MidnightBSD 0.1 ash compatibility mode is requested' && \
+    check_categories="$check_categories mnbsdash"
 
 #
 # Environment: headers
@@ -1529,7 +1532,7 @@ else
 		#define EXTERN
 		#define MKSH_INCLUDES_ONLY
 		#include "sh.h"
-		__RCSID("$MirOS: src/bin/mksh/Build.sh,v 1.621 2013/02/18 22:55:35 tg Exp $");
+		__RCSID("$MirOS: src/bin/mksh/Build.sh,v 1.622 2013/02/19 18:45:15 tg Exp $");
 		int main(void) { printf("Hello, World!\n"); return (0); }
 EOF
 	case $cm in
diff --git a/check.t b/check.t
index 8a90919..d33febd 100644
--- a/check.t
+++ b/check.t
@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.596 2013/02/18 22:55:37 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.597 2013/02/19 18:45:17 tg Exp $
 # $OpenBSD: bksl-nl.t,v 1.2 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: history.t,v 1.5 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: read.t,v 1.3 2003/03/10 03:48:16 david Exp $
@@ -29,7 +29,7 @@
 # http://www.freebsd.org/cgi/cvsweb.cgi/src/tools/regression/bin/test/regress.sh?rev=HEAD
 
 expected-stdout:
-	@(#)MIRBSD KSH R43 2013/02/18
+	@(#)MIRBSD KSH R43 2013/02/19
 description:
 	Check version of shell.
 stdin:
@@ -38,7 +38,7 @@ name: KSH_VERSION
 category: shell:legacy-no
 ---
 expected-stdout:
-	@(#)LEGACY KSH R43 2013/02/18
+	@(#)LEGACY KSH R43 2013/02/19
 description:
 	Check version of legacy shell.
 stdin:
@@ -6005,10 +6005,9 @@ description:
 stdin:
 	test \( -f = -f \)
 	rv=$?
-	test -n "$POSH_VERSION" || set -o sh
-	echo -e $rv
+	echo $rv
 expected-stdout:
-	-e 0
+	0
 ---
 name: test-option-1
 description:
@@ -10301,12 +10300,38 @@ description:
 	mandates it shall be treated as string but escapes
 	shall be expanded.
 stdin:
-	test -n "$POSH_VERSION" || set -o sh
+	test -n "$POSH_VERSION" || set -o posix
 	echo -n 'foo\x40bar'
 	echo -e '\tbaz'
 expected-stdout:
 	foo\x40bar-e \tbaz
 ---
+name: echo-test-3-mnbsd
+description:
+	Test what the echo builtin does, and test a compatibility flag.
+category: mnbsdash
+stdin:
+	"$__progname" -c 'echo -n 1=\\x40$1; echo -e \\x2E' -- foo bar
+	"$__progname" -o posix -c 'echo -n 2=\\x40$1; echo -e \\x2E' -- foo bar
+	"$__progname" -o sh -c 'echo -n 3=\\x40$1; echo -e \\x2E' -- foo bar
+expected-stdout:
+	1=@foo.
+	2=\x40foo-e \x2E
+	3=\x40bar.
+---
+name: echo-test-3-normal
+description:
+	Test what the echo builtin does, and test a compatibility flag.
+category: !mnbsdash
+stdin:
+	"$__progname" -c 'echo -n 1=\\x40$1; echo -e \\x2E' -- foo bar
+	"$__progname" -o posix -c 'echo -n 2=\\x40$1; echo -e \\x2E' -- foo bar
+	"$__progname" -o sh -c 'echo -n 3=\\x40$1; echo -e \\x2E' -- foo bar
+expected-stdout:
+	1=@foo.
+	2=\x40foo-e \x2E
+	3=\x40foo-e \x2E
+---
 name: utilities-getopts-1
 description:
 	getopts sets OPTIND correctly for unparsed option
diff --git a/lex.c b/lex.c
index cede51c..3f60742 100644
--- a/lex.c
+++ b/lex.c
@@ -23,7 +23,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/lex.c,v 1.181 2013/02/17 06:05:02 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/lex.c,v 1.182 2013/02/19 18:45:20 tg Exp $");
 
 /*
  * states while lexing word
@@ -1508,7 +1508,8 @@ set_prompt(int to, Source *s)
 static int
 dopprompt(const char *cp, int ntruncate, bool doprint)
 {
-	int columns = 0, lines = 0, indelimit = 0;
+	int columns = 0, lines = 0;
+	bool indelimit = false;
 	char delimiter = 0;
 
 	/*
diff --git a/mksh.1 b/mksh.1
index 649594a..51800fc 100644
--- a/mksh.1
+++ b/mksh.1
@@ -1,4 +1,4 @@
-.\" $MirOS: src/bin/mksh/mksh.1,v 1.304 2013/02/11 17:17:59 tg Exp $
+.\" $MirOS: src/bin/mksh/mksh.1,v 1.305 2013/02/19 18:45:20 tg Exp $
 .\" $OpenBSD: ksh.1,v 1.145 2013/01/17 21:20:25 jmc Exp $
 .\"-
 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
@@ -74,7 +74,7 @@
 .\" with -mandoc, it might implement .Mx itself, but we want to
 .\" use our own definition. And .Dd must come *first*, always.
 .\"
-.Dd $Mdocdate: February 11 2013 $
+.Dd $Mdocdate: February 19 2013 $
 .\"
 .\" Check which macro package we use, and do other -mdoc setup.
 .\"
@@ -6335,10 +6335,15 @@ $ /bin/sleep 666 && echo fubar
 .Ed
 .Pp
 This document attempts to describe
-.Nm mksh\ R42
+.Nm mksh\ R43
 and up,
 compiled without any options impacting functionality, such as
 .Dv MKSH_SMALL ,
+when not called as
+.Pa /bin/sh
+which, on some systems only, enables
+.Ic set \-o sh
+automatically (whose behaviour differs across targets),
 for an operating environment supporting all of its advanced needs.
 Please report bugs in
 .Nm
@@ -6351,4 +6356,6 @@ or in the
 .Pq or Li \&#ksh
 IRC channel at
 .Pa irc.freenode.net
-.Pq Port 6697 SSL, 6667 unencrypted .
+.Pq Port 6697 SSL, 6667 unencrypted ,
+or at:
+.Pa https://launchpad.net/mksh
diff --git a/sh.h b/sh.h
index 789bea0..c358058 100644
--- a/sh.h
+++ b/sh.h
@@ -164,9 +164,9 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.638 2013/02/18 22:55:40 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.639 2013/02/19 18:45:22 tg Exp $");
 #endif
-#define MKSH_VERSION "R43 2013/02/18"
+#define MKSH_VERSION "R43 2013/02/19"
 
 /* arithmetic types: C implementation */
 #if !HAVE_CAN_INTTYPES