diff --git a/Build.sh b/Build.sh
index d0c8240..dcd8da8 100644
--- a/Build.sh
+++ b/Build.sh
@@ -1,5 +1,5 @@
 #!/bin/sh
-srcversion='$MirOS: src/bin/mksh/Build.sh,v 1.491 2011/11/26 17:56:29 tg Exp $'
+srcversion='$MirOS: src/bin/mksh/Build.sh,v 1.492 2011/12/02 22:55:45 tg Exp $'
 #-
 # Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
 #	Thorsten Glaser <tg@mirbsd.org>
@@ -22,17 +22,7 @@ srcversion='$MirOS: src/bin/mksh/Build.sh,v 1.491 2011/11/26 17:56:29 tg Exp $'
 # People analysing the output must whitelist conftest.c for any kind
 # of compiler warning checks (mirtoconf is by design not quiet).
 #
-# Environment used:	CC CFLAGS CPPFLAGS LDFLAGS LIBS NOWARN NROFF
-#			TARGET_OS TARGET_OSREV
-# Feature selectors:	USE_PRINTF_BUILTIN
-# CPPFLAGS recognised:	MKSH_MIDNIGHTBSD01ASH_COMPAT MKSH_CONSERVATIVE_FDS
-#			MKSH_DONT_EMIT_IDSTRING MKSH_NO_DEPRECATED_WARNING
-#			MKSH_DISABLE_DEPRECATED MKSH_ASSUME_UTF8 MKSH_A4PB
-#			MKSH_SMALL MKSH_BINSHREDUCED MKSH_NOPROSPECTOFWORK
-#			MKSH_UNEMPLOYED MKSH_NO_LIMITS MKSH_DEFAULT_TMPDIR
-#			MKSH_DEFAULT_EXECSHELL MKSHRC_PATH MKSH_CLS_STRING
-#			MKSH_CLRTOEOL_STRING MKSH_NO_EXTERNAL_CAT
-#			MKSH_NOPWNAM MKSH_S_NOVI
+# Used environment documentation is at the end of this file.
 
 LC_ALL=C
 export LC_ALL
@@ -1183,7 +1173,7 @@ else
 		#define EXTERN
 		#define MKSH_INCLUDES_ONLY
 		#include "sh.h"
-		__RCSID("$MirOS: src/bin/mksh/Build.sh,v 1.491 2011/11/26 17:56:29 tg Exp $");
+		__RCSID("$MirOS: src/bin/mksh/Build.sh,v 1.492 2011/12/02 22:55:45 tg Exp $");
 		int main(void) { printf("Hello, World!\n"); return (0); }
 EOF
 	case $cm in
@@ -1785,3 +1775,51 @@ $e
 $e Run the regression test suite: ./test.sh
 $e Please also read the sample file dot.mkshrc and the fine manual.
 exit 0
+
+: <<'EOD'
+
+=== Environment used ===
+
+==== build environment ====
+CC				default: cc
+CFLAGS				if empty, defaults to -xO2 or +O2
+				or -O3 -qstrict or -O2, per compiler
+CPPFLAGS			default empty
+LDFLAGS				default empty; added before sources
+LIBS				default empty; added after sources
+				[Interix] default: -lcrypt (XXX still needed?)
+NOWARN				-Wno-error or similar
+NROFF				default: nroff
+TARGET_OS			default: $(uname -s || uname)
+TARGET_OSREV			[QNX] default: $(uname -r)
+
+==== feature selectors ====
+USE_PRINTF_BUILTIN		1 to include (unsupported) printf(1) as builtin
+===== general format =====
+HAVE_STRLEN			ac_test
+HAVE_STRING_H			ac_header
+HAVE_CAN_FSTACKPROTECTORALL	ac_flags
+
+==== cpp definitions ====
+MKSHRC_PATH			"~/.mkshrc" (do not change)
+MKSH_A4PB			force use of arc4random_pushb
+MKSH_ASSUME_UTF8		(0=disabled, 1=enabled; default: unset)
+MKSH_BINSHREDUCED		if */sh or */-sh, enable set -o sh
+MKSH_CLRTOEOL_STRING		"\033[K"
+MKSH_CLS_STRING			"\033[;H\033[J"
+MKSH_CONSERVATIVE_FDS		fd 0-9 for scripts, shell only up to 31
+MKSH_DEFAULT_EXECSHELL		"/bin/sh" (do not change)
+MKSH_DEFAULT_TMPDIR		"/tmp" (do not change)
+MKSH_DISABLE_DEPRECATED		disable code paths scheduled for later removal
+MKSH_DONT_EMIT_IDSTRING		omit RCS IDs from binary
+MKSH_MIDNIGHTBSD01ASH_COMPAT	set -o sh: additional compatibility quirk
+MKSH_NOPROSPECTOFWORK		disable jobs, co-processes, etc. (do not use)
+MKSH_NOPWNAM			skip PAM calls, for -static on eglibc, Solaris
+MKSH_NO_DEPRECATED_WARNING	omit warning when deprecated stuff is run
+MKSH_NO_EXTERNAL_CAT		omit hack to skip cat builtin when flags passed
+MKSH_NO_LIMITS			omit ulimit code
+MKSH_SMALL			omit some code, optimise hard for size (slower)
+MKSH_S_NOVI			disable Vi editing mode (default if MKSH_SMALL)
+MKSH_UNEMPLOYED			disable job control (but not jobs/co-processes)
+
+EOD
diff --git a/check.t b/check.t
index e81563e..e2f3bba 100644
--- a/check.t
+++ b/check.t
@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.497 2011/11/30 21:34:10 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.498 2011/12/02 22:55:46 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 $
@@ -28,7 +28,7 @@
 # http://www.freebsd.org/cgi/cvsweb.cgi/src/tools/regression/bin/test/regress.sh?rev=HEAD
 
 expected-stdout:
-	@(#)MIRBSD KSH R40 2011/11/30
+	@(#)MIRBSD KSH R40 2011/12/02
 description:
 	Check version of shell.
 stdin:
diff --git a/funcs.c b/funcs.c
index 14e5899..1160991 100644
--- a/funcs.c
+++ b/funcs.c
@@ -38,7 +38,7 @@
 #endif
 #endif
 
-__RCSID("$MirOS: src/bin/mksh/funcs.c,v 1.200 2011/11/30 21:34:12 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/funcs.c,v 1.201 2011/12/02 22:55:48 tg Exp $");
 
 #if HAVE_KILLPG
 /*
@@ -2697,7 +2697,7 @@ c_mknod(const char **wp)
 #endif
 
 /*-
-   test(1) accepts the following grammar:
+   test(1) roughly accepts the following grammar:
 	oexpr	::= aexpr | aexpr "-o" oexpr ;
 	aexpr	::= nexpr | nexpr "-a" aexpr ;
 	nexpr	::= primary | "!" nexpr ;
@@ -2713,13 +2713,13 @@ c_mknod(const char **wp)
 
 	binary-operator ::= "="|"=="|"!="|"-eq"|"-ne"|"-ge"|"-gt"|"-le"|"-lt"|
 			    "-nt"|"-ot"|"-ef"|
-			    "<"|">"	# rules used for [[ .. ]] expressions
+			    "<"|">"	# rules used for [[ ... ]] expressions
 			    ;
-	operand ::= <any thing>
+	operand ::= <anything>
 */
 
 /* POSIX says > 1 for errors */
-#define T_ERR_EXIT	2
+#define T_ERR_EXIT 2
 
 int
 c_test(const char **wp)
@@ -2778,19 +2778,13 @@ c_test(const char **wp)
 	case 3:
  ptest_three:
 		swp = te.pos.wp;
-		/* skip lhs, without evaluation */
-		(*te.getopnd)(&te, TO_NONOP, false);
+		/* inside knowledge shows ptest_getopnd never evaluates */
+		/* skip lhs, without evaluation; assign with */
+		lhs = (*te.getopnd)(&te, TO_NONOP, true);
 		if ((op = (*te.isa)(&te, TM_BINOP))) {
-			const char *rhs;
-
-			/* read rhs, with evaluation */
-			rhs = (*te.getopnd)(&te, op, true);
-			/* back up to lhs */
-			te.pos.wp = swp;
-			/* re-read lhs, with evaluation */
-			lhs = (*te.getopnd)(&te, op, true);
-			/* finally run the test of lhs op rhs */
-			rv = (*te.eval)(&te, op, lhs, rhs, true);
+			/* test lhs op rhs */
+			rv = (*te.eval)(&te, op, lhs,
+			    (*te.getopnd)(&te, op, true), true);
 			goto ptest_out;
 		}
 		/* back up to lhs */
diff --git a/sh.h b/sh.h
index 51d46de..fea71c2 100644
--- a/sh.h
+++ b/sh.h
@@ -151,9 +151,9 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.506 2011/11/30 21:34:15 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.507 2011/12/02 22:55:49 tg Exp $");
 #endif
-#define MKSH_VERSION "R40 2011/11/30"
+#define MKSH_VERSION "R40 2011/12/02"
 
 #ifndef MKSH_INCLUDES_ONLY