diff --git a/bin/sh/Makefile b/bin/sh/Makefile
index 337264b54b0c..e3c25e126d8d 100644
--- a/bin/sh/Makefile
+++ b/bin/sh/Makefile
@@ -62,4 +62,7 @@ syntax.c syntax.h: mksyntax
 token.h: mktokens
 	sh ${.CURDIR}/mktokens
 
+regress:
+	cd ${.CURDIR}/../../tools/regression/bin/sh && ${MAKE} SH=${.OBJDIR}/sh
+
 .include <bsd.prog.mk>
diff --git a/tools/regression/bin/sh/Makefile b/tools/regression/bin/sh/Makefile
index 2c9ca5943505..82b9c09f2c2e 100644
--- a/tools/regression/bin/sh/Makefile
+++ b/tools/regression/bin/sh/Makefile
@@ -1,4 +1,7 @@
 # $FreeBSD$
 
+# Allow one to specify the 'sh' to regress.
+SH?=	/bin/sh
+
 all:
-	sh regress.sh
+	env SH=${SH} ${SH} regress.sh
diff --git a/tools/regression/bin/sh/builtins/command8.0 b/tools/regression/bin/sh/builtins/command8.0
index 949ffedaee9f..9e3a2b645fbb 100644
--- a/tools/regression/bin/sh/builtins/command8.0
+++ b/tools/regression/bin/sh/builtins/command8.0
@@ -22,7 +22,7 @@ set -e
 set -- ${SPECIAL}
 for cmd in "$@"
 do
-	sh -c "v=:; while \$v; do v=false; command ${cmd}; done" >/dev/null
+	${SH} -c "v=:; while \$v; do v=false; command ${cmd}; done" >/dev/null
 done
 
 while :; do
diff --git a/tools/regression/bin/sh/builtins/exec1.0 b/tools/regression/bin/sh/builtins/exec1.0
index 94af2a08f3cd..dd30a4c9aa93 100644
--- a/tools/regression/bin/sh/builtins/exec1.0
+++ b/tools/regression/bin/sh/builtins/exec1.0
@@ -12,7 +12,7 @@ failure() {
 )
 [ $? = 0 ] || failure $LINENO
 (
-	exec sh -c 'exit 42'
+	exec ${SH} -c 'exit 42'
 	echo bad
 )
 [ $? = 42 ] || failure $LINENO
diff --git a/tools/regression/bin/sh/builtins/exec2.0 b/tools/regression/bin/sh/builtins/exec2.0
index a04bf34d4502..3dcb6c41156a 100644
--- a/tools/regression/bin/sh/builtins/exec2.0
+++ b/tools/regression/bin/sh/builtins/exec2.0
@@ -12,7 +12,7 @@ failure() {
 )
 [ $? = 0 ] || failure $LINENO
 (
-	exec -- sh -c 'exit 42'
+	exec -- ${SH} -c 'exit 42'
 	echo bad
 )
 [ $? = 42 ] || failure $LINENO
diff --git a/tools/regression/bin/sh/builtins/fc1.0 b/tools/regression/bin/sh/builtins/fc1.0
index 59d10ef6d2e1..ab7a387b5077 100644
--- a/tools/regression/bin/sh/builtins/fc1.0
+++ b/tools/regression/bin/sh/builtins/fc1.0
@@ -8,7 +8,7 @@ T=$(mktemp -d sh-test.XXXXXX)
 cd $T
 
 mkfifo input output error
-HISTFILE=/dev/null sh +m -i <input >output 2>error &
+HISTFILE=/dev/null ${SH} +m -i <input >output 2>error &
 {
 	# Syntax error
 	echo ')' >&3
diff --git a/tools/regression/bin/sh/builtins/fc2.0 b/tools/regression/bin/sh/builtins/fc2.0
index 4f696d480be9..7eb92acc2cdf 100644
--- a/tools/regression/bin/sh/builtins/fc2.0
+++ b/tools/regression/bin/sh/builtins/fc2.0
@@ -8,7 +8,7 @@ T=$(mktemp -d sh-test.XXXXXX)
 cd $T
 
 mkfifo input output error
-HISTFILE=/dev/null sh +m -i <input >output 2>error &
+HISTFILE=/dev/null ${SH} +m -i <input >output 2>error &
 exec 3>input
 {
 	# Command not found, containing slash
diff --git a/tools/regression/bin/sh/builtins/trap1.0 b/tools/regression/bin/sh/builtins/trap1.0
index 1a87f4cb7f8c..313f6a387678 100644
--- a/tools/regression/bin/sh/builtins/trap1.0
+++ b/tools/regression/bin/sh/builtins/trap1.0
@@ -4,11 +4,11 @@ test "$(trap 'echo trapped' EXIT; :)" = trapped || exit 1
 
 test "$(trap 'echo trapped' EXIT; /usr/bin/true)" = trapped || exit 1
 
-result=$(sh -c 'trap "echo trapped" EXIT; /usr/bin/false')
+result=$(${SH} -c 'trap "echo trapped" EXIT; /usr/bin/false')
 test $? -eq 1 || exit 1
 test "$result" = trapped || exit 1
 
-result=$(sh -c 'trap "echo trapped" EXIT; exec /usr/bin/false')
+result=$(${SH} -c 'trap "echo trapped" EXIT; exec /usr/bin/false')
 test $? -eq 1 || exit 1
 test -z "$result" || exit 1
 
diff --git a/tools/regression/bin/sh/builtins/var-assign.0 b/tools/regression/bin/sh/builtins/var-assign.0
index 2e57a3190ca1..ace39c042d5f 100644
--- a/tools/regression/bin/sh/builtins/var-assign.0
+++ b/tools/regression/bin/sh/builtins/var-assign.0
@@ -44,12 +44,12 @@ set -e
 set -- ${SPECIAL}
 for cmd in "$@"
 do
-	sh -c "VAR=1; VAR=0 ${cmd}; exit \${VAR}" >/dev/null 2>&1
+	${SH} -c "VAR=1; VAR=0 ${cmd}; exit \${VAR}" >/dev/null 2>&1
 done
 
 # For other built-ins and utilites they do not.
 set -- ${UTILS}
 for cmd in "$@"
 do
-	sh -c "VAR=0; VAR=1 ${cmd}; exit \${VAR}" >/dev/null 2>&1
+	${SH} -c "VAR=0; VAR=1 ${cmd}; exit \${VAR}" >/dev/null 2>&1
 done
diff --git a/tools/regression/bin/sh/builtins/var-assign2.0 b/tools/regression/bin/sh/builtins/var-assign2.0
index b7dbaf78c2ab..eafec89a681b 100644
--- a/tools/regression/bin/sh/builtins/var-assign2.0
+++ b/tools/regression/bin/sh/builtins/var-assign2.0
@@ -45,11 +45,11 @@ set -e
 set -- ${SPECIAL}
 for cmd in "$@"
 do
-	sh -c "VAR=0; VAR=1 command ${cmd}; exit \${VAR}" >/dev/null 2>&1
+	${SH} -c "VAR=0; VAR=1 command ${cmd}; exit \${VAR}" >/dev/null 2>&1
 done
 
 set -- ${UTILS}
 for cmd in "$@"
 do
-	sh -c "VAR=0; VAR=1 command ${cmd}; exit \${VAR}" >/dev/null 2>&1
+	${SH} -c "VAR=0; VAR=1 command ${cmd}; exit \${VAR}" >/dev/null 2>&1
 done
diff --git a/tools/regression/bin/sh/errors/assignment-error1.0 b/tools/regression/bin/sh/errors/assignment-error1.0
index c999b41b447f..00eaed9b8671 100644
--- a/tools/regression/bin/sh/errors/assignment-error1.0
+++ b/tools/regression/bin/sh/errors/assignment-error1.0
@@ -16,15 +16,15 @@ SPECIAL="break,\
 	unset foo"
 
 # If there is no command word, the shell must abort on an assignment error.
-sh -c "readonly a=0; a=2; exit 0" 2>/dev/null && exit 1
+${SH} -c "readonly a=0; a=2; exit 0" 2>/dev/null && exit 1
 
 # Special built-in utilities must abort on an assignment error.
 set -- ${SPECIAL}
 for cmd in "$@"
 do
-	sh -c "readonly a=0; a=2 ${cmd}; exit 0" 2>/dev/null && exit 1
+	${SH} -c "readonly a=0; a=2 ${cmd}; exit 0" 2>/dev/null && exit 1
 done
 
 # Other utilities must not abort; we currently still execute them.
-sh -c 'readonly a=0; a=1 true; exit $a' 2>/dev/null || exit 1
-sh -c 'readonly a=0; a=1 command :; exit $a' 2>/dev/null || exit 1
+${SH} -c 'readonly a=0; a=1 true; exit $a' 2>/dev/null || exit 1
+${SH} -c 'readonly a=0; a=1 command :; exit $a' 2>/dev/null || exit 1
diff --git a/tools/regression/bin/sh/errors/backquote-error1.0 b/tools/regression/bin/sh/errors/backquote-error1.0
index 2a40c88e1be7..43e33034af9f 100644
--- a/tools/regression/bin/sh/errors/backquote-error1.0
+++ b/tools/regression/bin/sh/errors/backquote-error1.0
@@ -1,4 +1,4 @@
 # $FreeBSD$
 
-echo 'echo `for` echo ".BAD"CODE.' | sh +m -i 2>&1 | grep -q BADCODE && exit 1
+echo 'echo `for` echo ".BAD"CODE.' | ${SH} +m -i 2>&1 | grep -q BADCODE && exit 1
 exit 0
diff --git a/tools/regression/bin/sh/errors/backquote-error2.0 b/tools/regression/bin/sh/errors/backquote-error2.0
index 977c055a2af1..5b49e2be17ce 100644
--- a/tools/regression/bin/sh/errors/backquote-error2.0
+++ b/tools/regression/bin/sh/errors/backquote-error2.0
@@ -1,7 +1,7 @@
 # $FreeBSD$
 
-sh -c 'echo `echo .BA"DCODE.`
+${SH} -c 'echo `echo .BA"DCODE.`
 echo ".BAD"CODE.' 2>&1 | grep -q BADCODE && exit 1
-echo '`"`' | sh -n 2>/dev/null && exit 1
-echo '`'"'"'`' | sh -n 2>/dev/null && exit 1
+echo '`"`' | ${SH} -n 2>/dev/null && exit 1
+echo '`'"'"'`' | ${SH} -n 2>/dev/null && exit 1
 exit 0
diff --git a/tools/regression/bin/sh/errors/option-error.0 b/tools/regression/bin/sh/errors/option-error.0
index f599d59072cc..b4b44c4a4062 100644
--- a/tools/regression/bin/sh/errors/option-error.0
+++ b/tools/regression/bin/sh/errors/option-error.0
@@ -35,12 +35,12 @@ UTILS="alias -y,\
 set -- ${SPECIAL}
 for cmd in "$@"
 do
-	sh -c "${cmd}; exit 0" 2>/dev/null && exit 1
+	${SH} -c "${cmd}; exit 0" 2>/dev/null && exit 1
 done
 
 # Other utilities must not abort.
 set -- ${UTILS}
 for cmd in "$@"
 do
-	sh -c "${cmd}; exit 0" 2>/dev/null || exit 1
+	${SH} -c "${cmd}; exit 0" 2>/dev/null || exit 1
 done
diff --git a/tools/regression/bin/sh/errors/redirection-error.0 b/tools/regression/bin/sh/errors/redirection-error.0
index d11118a9c9fa..cb8c0b113c13 100644
--- a/tools/regression/bin/sh/errors/redirection-error.0
+++ b/tools/regression/bin/sh/errors/redirection-error.0
@@ -42,12 +42,12 @@ UTILS="alias,\
 set -- ${SPECIAL}
 for cmd in "$@"
 do
-	sh -c "${cmd} > /; exit 0" 2>/dev/null && exit 1
+	${SH} -c "${cmd} > /; exit 0" 2>/dev/null && exit 1
 done
 
 # Other utilities must not abort.
 set -- ${UTILS}
 for cmd in "$@"
 do
-	sh -c "${cmd} > /; exit 0" 2>/dev/null || exit 1
+	${SH} -c "${cmd} > /; exit 0" 2>/dev/null || exit 1
 done
diff --git a/tools/regression/bin/sh/errors/redirection-error2.2 b/tools/regression/bin/sh/errors/redirection-error2.2
index 2117ecf07700..32bccd8e784a 100644
--- a/tools/regression/bin/sh/errors/redirection-error2.2
+++ b/tools/regression/bin/sh/errors/redirection-error2.2
@@ -1,4 +1,4 @@
 # $FreeBSD$
 
 # sh should fail gracefully on this bad redirect
-sh -c 'echo 1 >&$a' 2>/dev/null
+${SH} -c 'echo 1 >&$a' 2>/dev/null
diff --git a/tools/regression/bin/sh/errors/redirection-error3.0 b/tools/regression/bin/sh/errors/redirection-error3.0
index 93f526c7a125..8a07d037baec 100644
--- a/tools/regression/bin/sh/errors/redirection-error3.0
+++ b/tools/regression/bin/sh/errors/redirection-error3.0
@@ -44,11 +44,11 @@ UTILS="alias,\
 set -- ${SPECIAL}
 for cmd in "$@"
 do
-	sh -c "command ${cmd} > /; exit 0" 2>/dev/null || exit 1
+	${SH} -c "command ${cmd} > /; exit 0" 2>/dev/null || exit 1
 done
 
 set -- ${UTILS}
 for cmd in "$@"
 do
-	sh -c "command ${cmd} > /; exit 0" 2>/dev/null || exit 1
+	${SH} -c "command ${cmd} > /; exit 0" 2>/dev/null || exit 1
 done
diff --git a/tools/regression/bin/sh/execution/fork1.0 b/tools/regression/bin/sh/execution/fork1.0
index 3ed5de2ec1f1..225a82593231 100644
--- a/tools/regression/bin/sh/execution/fork1.0
+++ b/tools/regression/bin/sh/execution/fork1.0
@@ -1,7 +1,7 @@
 # $FreeBSD$
 
-result=$(sh -c 'ps -p $$ -o comm=')
+result=$(${SH} -c 'ps -p $$ -o comm=')
 test "$result" = "ps" || exit 1
 
-result=$(sh -c 'ps -p $$ -o comm=; :')
+result=$(${SH} -c 'ps -p $$ -o comm=; :')
 test "$result" = "sh" || exit 1
diff --git a/tools/regression/bin/sh/execution/fork2.0 b/tools/regression/bin/sh/execution/fork2.0
index 35ea3a34df9a..62a25379123c 100644
--- a/tools/regression/bin/sh/execution/fork2.0
+++ b/tools/regression/bin/sh/execution/fork2.0
@@ -1,9 +1,9 @@
 # $FreeBSD$
 
-result=$(sh -c '(/bin/sleep 1)& sleep 0.1; ps -p $! -o comm=; kill $!')
+result=$(${SH} -c '(/bin/sleep 1)& sleep 0.1; ps -p $! -o comm=; kill $!')
 test "$result" = sleep || exit 1
 
-result=$(sh -c '{ trap "echo trapped" EXIT; (/usr/bin/true); } & wait')
+result=$(${SH} -c '{ trap "echo trapped" EXIT; (/usr/bin/true); } & wait')
 test "$result" = trapped || exit 1
 
 exit 0
diff --git a/tools/regression/bin/sh/execution/func1.0 b/tools/regression/bin/sh/execution/func1.0
index 317b00588686..29fcc077b592 100644
--- a/tools/regression/bin/sh/execution/func1.0
+++ b/tools/regression/bin/sh/execution/func1.0
@@ -1,4 +1,4 @@
 # $FreeBSD$
 
-MALLOC_OPTIONS=J sh -c 'g() { g() { :; }; :; }; g' &&
-MALLOC_OPTIONS=J sh -c 'g() { unset -f g; :; }; g'
+MALLOC_OPTIONS=J ${SH} -c 'g() { g() { :; }; :; }; g' &&
+MALLOC_OPTIONS=J ${SH} -c 'g() { unset -f g; :; }; g'
diff --git a/tools/regression/bin/sh/execution/redir2.0 b/tools/regression/bin/sh/execution/redir2.0
index 697662470d49..1588105f599a 100644
--- a/tools/regression/bin/sh/execution/redir2.0
+++ b/tools/regression/bin/sh/execution/redir2.0
@@ -10,7 +10,7 @@ brokenpipe=0
 mkfifo fifo1 fifo2
 {
 	{
-		exec sh -c 'exec <fifo1; read dummy'
+		exec ${SH} -c 'exec <fifo1; read dummy'
 	} 7<&- # fifo2 should be kept open, but not passed to programs
 	true
 } 7<fifo2 &
diff --git a/tools/regression/bin/sh/expansion/question1.0 b/tools/regression/bin/sh/expansion/question1.0
index 355af624aa6d..663c68d2046d 100644
--- a/tools/regression/bin/sh/expansion/question1.0
+++ b/tools/regression/bin/sh/expansion/question1.0
@@ -6,17 +6,17 @@ set -- ${x?}
 { [ "$#" = 2 ] && [ "$1" = a ] && [ "$2" = b ]; } || exit 1
 unset x
 (echo ${x?abcdefg}) 2>&1 | grep -q abcdefg || exit 1
-sh -c 'unset foo; echo ${foo?}' 2>/dev/null && exit 1
-sh -c 'foo=; echo ${foo:?}' 2>/dev/null && exit 1
-sh -c 'foo=; echo ${foo?}' >/dev/null || exit 1
-sh -c 'foo=1; echo ${foo:?}' >/dev/null || exit 1
-sh -c 'echo ${!?}' 2>/dev/null && exit 1
-sh -c ':& echo ${!?}' >/dev/null || exit 1
-sh -c 'echo ${#?}' >/dev/null || exit 1
-sh -c 'echo ${*?}' 2>/dev/null && exit 1
-sh -c 'echo ${*?}' sh x >/dev/null || exit 1
-sh -c 'echo ${1?}' 2>/dev/null && exit 1
-sh -c 'echo ${1?}' sh x >/dev/null || exit 1
-sh -c 'echo ${2?}' sh x 2>/dev/null && exit 1
-sh -c 'echo ${2?}' sh x y >/dev/null || exit 1
+${SH} -c 'unset foo; echo ${foo?}' 2>/dev/null && exit 1
+${SH} -c 'foo=; echo ${foo:?}' 2>/dev/null && exit 1
+${SH} -c 'foo=; echo ${foo?}' >/dev/null || exit 1
+${SH} -c 'foo=1; echo ${foo:?}' >/dev/null || exit 1
+${SH} -c 'echo ${!?}' 2>/dev/null && exit 1
+${SH} -c ':& echo ${!?}' >/dev/null || exit 1
+${SH} -c 'echo ${#?}' >/dev/null || exit 1
+${SH} -c 'echo ${*?}' 2>/dev/null && exit 1
+${SH} -c 'echo ${*?}' ${SH} x >/dev/null || exit 1
+${SH} -c 'echo ${1?}' 2>/dev/null && exit 1
+${SH} -c 'echo ${1?}' ${SH} x >/dev/null || exit 1
+${SH} -c 'echo ${2?}' ${SH} x 2>/dev/null && exit 1
+${SH} -c 'echo ${2?}' ${SH} x y >/dev/null || exit 1
 exit 0
diff --git a/tools/regression/bin/sh/expansion/set-u1.0 b/tools/regression/bin/sh/expansion/set-u1.0
index a66bfc9dc99b..763eb7dcfc8f 100644
--- a/tools/regression/bin/sh/expansion/set-u1.0
+++ b/tools/regression/bin/sh/expansion/set-u1.0
@@ -1,29 +1,29 @@
 # $FreeBSD$
 
-sh -uc 'unset foo; echo $foo' 2>/dev/null && exit 1
-sh -uc 'foo=; echo $foo' >/dev/null || exit 1
-sh -uc 'foo=1; echo $foo' >/dev/null || exit 1
+${SH} -uc 'unset foo; echo $foo' 2>/dev/null && exit 1
+${SH} -uc 'foo=; echo $foo' >/dev/null || exit 1
+${SH} -uc 'foo=1; echo $foo' >/dev/null || exit 1
 # -/+/= are unaffected by set -u
-sh -uc 'unset foo; echo ${foo-}' >/dev/null || exit 1
-sh -uc 'unset foo; echo ${foo+}' >/dev/null || exit 1
-sh -uc 'unset foo; echo ${foo=}' >/dev/null || exit 1
+${SH} -uc 'unset foo; echo ${foo-}' >/dev/null || exit 1
+${SH} -uc 'unset foo; echo ${foo+}' >/dev/null || exit 1
+${SH} -uc 'unset foo; echo ${foo=}' >/dev/null || exit 1
 # length/trimming are affected
-sh -uc 'unset foo; echo ${#foo}' 2>/dev/null && exit 1
-sh -uc 'foo=; echo ${#foo}' >/dev/null || exit 1
-sh -uc 'unset foo; echo ${foo#?}' 2>/dev/null && exit 1
-sh -uc 'foo=1; echo ${foo#?}' >/dev/null || exit 1
-sh -uc 'unset foo; echo ${foo##?}' 2>/dev/null && exit 1
-sh -uc 'foo=1; echo ${foo##?}' >/dev/null || exit 1
-sh -uc 'unset foo; echo ${foo%?}' 2>/dev/null && exit 1
-sh -uc 'foo=1; echo ${foo%?}' >/dev/null || exit 1
-sh -uc 'unset foo; echo ${foo%%?}' 2>/dev/null && exit 1
-sh -uc 'foo=1; echo ${foo%%?}' >/dev/null || exit 1
+${SH} -uc 'unset foo; echo ${#foo}' 2>/dev/null && exit 1
+${SH} -uc 'foo=; echo ${#foo}' >/dev/null || exit 1
+${SH} -uc 'unset foo; echo ${foo#?}' 2>/dev/null && exit 1
+${SH} -uc 'foo=1; echo ${foo#?}' >/dev/null || exit 1
+${SH} -uc 'unset foo; echo ${foo##?}' 2>/dev/null && exit 1
+${SH} -uc 'foo=1; echo ${foo##?}' >/dev/null || exit 1
+${SH} -uc 'unset foo; echo ${foo%?}' 2>/dev/null && exit 1
+${SH} -uc 'foo=1; echo ${foo%?}' >/dev/null || exit 1
+${SH} -uc 'unset foo; echo ${foo%%?}' 2>/dev/null && exit 1
+${SH} -uc 'foo=1; echo ${foo%%?}' >/dev/null || exit 1
 
-sh -uc 'echo $!' 2>/dev/null && exit 1
-sh -uc ':& echo $!' >/dev/null || exit 1
-sh -uc 'echo $#' >/dev/null || exit 1
-sh -uc 'echo $1' 2>/dev/null && exit 1
-sh -uc 'echo $1' sh x >/dev/null || exit 1
-sh -uc 'echo $2' sh x 2>/dev/null && exit 1
-sh -uc 'echo $2' sh x y >/dev/null || exit 1
+${SH} -uc 'echo $!' 2>/dev/null && exit 1
+${SH} -uc ':& echo $!' >/dev/null || exit 1
+${SH} -uc 'echo $#' >/dev/null || exit 1
+${SH} -uc 'echo $1' 2>/dev/null && exit 1
+${SH} -uc 'echo $1' ${SH} x >/dev/null || exit 1
+${SH} -uc 'echo $2' ${SH} x 2>/dev/null && exit 1
+${SH} -uc 'echo $2' ${SH} x y >/dev/null || exit 1
 exit 0
diff --git a/tools/regression/bin/sh/parameters/mail1.0 b/tools/regression/bin/sh/parameters/mail1.0
index 26308eadbdc4..5791a5accc7c 100644
--- a/tools/regression/bin/sh/parameters/mail1.0
+++ b/tools/regression/bin/sh/parameters/mail1.0
@@ -4,7 +4,7 @@
 goodfile=/var/empty/sh-test-goodfile
 mailfile=/var/empty/sh-test-mailfile
 T=$(mktemp sh-test.XXXXXX) || exit
-MAIL=$mailfile ktrace -i -f "$T" sh -c "[ -s $goodfile ]" 2>/dev/null
+MAIL=$mailfile ktrace -i -f "$T" ${SH} -c "[ -s $goodfile ]" 2>/dev/null
 if ! grep -q $goodfile "$T"; then
 	# ktrace problem
 	rc=0
diff --git a/tools/regression/bin/sh/parameters/mail2.0 b/tools/regression/bin/sh/parameters/mail2.0
index e3b7da341328..343c99de9b27 100644
--- a/tools/regression/bin/sh/parameters/mail2.0
+++ b/tools/regression/bin/sh/parameters/mail2.0
@@ -4,7 +4,7 @@
 goodfile=/var/empty/sh-test-goodfile
 mailfile=/var/empty/sh-test-mailfile
 T=$(mktemp sh-test.XXXXXX) || exit
-ENV=$goodfile MAIL=$mailfile ktrace -i -f "$T" sh +m -i </dev/null >/dev/null 2>&1
+ENV=$goodfile MAIL=$mailfile ktrace -i -f "$T" ${SH} +m -i </dev/null >/dev/null 2>&1
 if ! grep -q $goodfile "$T"; then
 	# ktrace problem
 	rc=0
diff --git a/tools/regression/bin/sh/parameters/pwd1.0 b/tools/regression/bin/sh/parameters/pwd1.0
index d54303065ed5..0099379a9d3c 100644
--- a/tools/regression/bin/sh/parameters/pwd1.0
+++ b/tools/regression/bin/sh/parameters/pwd1.0
@@ -3,9 +3,9 @@
 
 cd / || exit 3
 failures=0
-[ "$(PWD=foo sh -c 'pwd')" = / ] || : $((failures += 1))
-[ "$(PWD=/var/empty sh -c 'pwd')" = / ] || : $((failures += 1))
-[ "$(PWD=/var/empty/foo sh -c 'pwd')" = / ] || : $((failures += 1))
-[ "$(PWD=/bin/ls sh -c 'pwd')" = / ] || : $((failures += 1))
+[ "$(PWD=foo ${SH} -c 'pwd')" = / ] || : $((failures += 1))
+[ "$(PWD=/var/empty ${SH} -c 'pwd')" = / ] || : $((failures += 1))
+[ "$(PWD=/var/empty/foo ${SH} -c 'pwd')" = / ] || : $((failures += 1))
+[ "$(PWD=/bin/ls ${SH} -c 'pwd')" = / ] || : $((failures += 1))
 
 exit $((failures != 0))
diff --git a/tools/regression/bin/sh/parameters/pwd2.0 b/tools/regression/bin/sh/parameters/pwd2.0
index 29b5531aaa85..2297f8b753d4 100644
--- a/tools/regression/bin/sh/parameters/pwd2.0
+++ b/tools/regression/bin/sh/parameters/pwd2.0
@@ -12,13 +12,13 @@ cd link
 [ "$PWD" = "$TP/link" ]
 [ "$(pwd)" = "$TP/link" ]
 [ "$(pwd -P)" = "$TP/test1" ]
-[ "$(sh -c pwd)" = "$TP/link" ]
-[ "$(sh -c pwd\ -P)" = "$TP/test1" ]
+[ "$(${SH} -c pwd)" = "$TP/link" ]
+[ "$(${SH} -c pwd\ -P)" = "$TP/test1" ]
 cd ..
 [ "$(pwd)" = "$TP" ]
 cd -P link
 [ "$PWD" = "$TP/test1" ]
 [ "$(pwd)" = "$TP/test1" ]
 [ "$(pwd -P)" = "$TP/test1" ]
-[ "$(sh -c pwd)" = "$TP/test1" ]
-[ "$(sh -c pwd\ -P)" = "$TP/test1" ]
+[ "$(${SH} -c pwd)" = "$TP/test1" ]
+[ "$(${SH} -c pwd\ -P)" = "$TP/test1" ]
diff --git a/tools/regression/bin/sh/regress.sh b/tools/regression/bin/sh/regress.sh
index a6889af50129..f4c389aa81df 100644
--- a/tools/regression/bin/sh/regress.sh
+++ b/tools/regression/bin/sh/regress.sh
@@ -1,12 +1,18 @@
 # $FreeBSD$
 
+if [ -z "${SH}" ]; then
+	echo '${SH} is not set, please correct and re-run.'
+	exit 1
+fi
+export SH=${SH}
+
 COUNTER=1
 
 do_test() {
 	local c
 	c=${COUNTER}
 	COUNTER=$((COUNTER+1))
-	sh $1 > tmp.stdout 2> tmp.stderr
+	${SH} $1 > tmp.stdout 2> tmp.stderr
 	if [ $? -ne $2 ]; then
 		echo "not ok ${c} - ${1} # wrong exit status"
 		rm tmp.stdout tmp.stderr
diff --git a/tools/regression/bin/sh/regress.t b/tools/regression/bin/sh/regress.t
index c36d8342d32a..2ae4fdb84a48 100644
--- a/tools/regression/bin/sh/regress.t
+++ b/tools/regression/bin/sh/regress.t
@@ -1,6 +1,12 @@
 #!/bin/sh
 # $FreeBSD$
 
+if [ -z "${SH}" ]; then
+	echo '${SH} is not set, please correct and re-run.'
+	exit 1
+fi
+export SH=${SH}
+
 cd `dirname $0`
 
-sh regress.sh
+${SH} regress.sh