diff --git a/.gitignore b/.gitignore
index 28753c14..29fc9994 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,13 +14,17 @@
 *.hex2
 *.hex2-o
 *.log
-*.stderr
-*.stdout
+*.mes-o
+*.mes-stdout
 *.mini-M1
 *.mini-guile
 *.mini-hex2
 *.mlibc-gcc
 *.mlibc-o
+*.mlibc-out
+*.mlibc-stdout
+*.stderr
+*.stdout
 *.tcc-guile
 !/stage0/*
 !/stage0/*.c
diff --git a/GNUmakefile b/GNUmakefile
index 9025f243..d1b1c3d4 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -3,9 +3,6 @@ GUILE_FLAGS:=--no-auto-compile -L . -L guile -C . -C guile
 
 include .config.make
 
-export PREFIX
-export VERSION
-
 PHONY_TARGETS:= all all-go check clean clean-go default help install
 .PHONY: $(PHONY_TARGETS)
 
@@ -37,3 +34,61 @@ seed:
 	MES=guile GUILE=guile SEED=1 build-aux/build-mes.sh
 	cd ../mes-seed && ./bootstrap.sh && cd ../mes
 	MES=guile GUILE=guile SEED=1 build-aux/build-mes.sh
+
+ifdef PREFIX
+export PREFIX
+endif
+
+ifdef VERSION
+export VERSION
+endif
+
+ifdef CC
+export CC
+endif
+
+ifdef CC32
+export CC32
+endif
+
+ifdef M1
+export M1
+endif
+
+ifdef HEX2
+export HEX2
+endif
+
+ifdef GUILE
+export GUILE
+endif
+
+ifdef GUILE_LOAD_PATH
+export GUILE_LOAD_PATH
+endif
+
+ifdef GUILE_LOAD_COMPILED_PATH
+export GUILE_LOAD_COMPILED_PATH
+endif
+
+ifdef CFLAGS
+export CFLAGS
+endif
+
+ifdef C32FLAGS
+export C32FLAGS
+endif
+
+ifdef HEX2FLAGS
+export HEX2FLAGS
+endif
+
+ifdef M1FLAGS
+export M1FLAGS
+endif
+
+ifdef MESCCFLAGS
+export MESCCFLAGS
+endif
+
+
diff --git a/build-aux/build-cc.sh b/build-aux/build-cc.sh
index 05796972..930c97bd 100755
--- a/build-aux/build-cc.sh
+++ b/build-aux/build-cc.sh
@@ -20,7 +20,23 @@
 
 set -ex
 
-export CC=${CC-gcc}
+export CC CFLAGS CPPFLAGS
+
+CC=${CC-gcc}
+CFLAGS=${CFLAGS-"
+--std=gnu99
+-O0
+-g
+"}
+
+CPPFLAGS=${CPPFLAGS-"
+-D VERSION=\"$VERSION\"
+-D MODULEDIR=\"$MODULEDIR\"
+-D PREFIX=\"$PREFIX\"
+-I src
+-I lib
+-I include
+"}
 
 build-aux/mes-snarf.scm src/gc.c
 build-aux/mes-snarf.scm src/lib.c
@@ -30,21 +46,6 @@ build-aux/mes-snarf.scm src/posix.c
 build-aux/mes-snarf.scm src/reader.c
 build-aux/mes-snarf.scm src/vector.c
 
-export CPPFLAGS=${CPPFLAGS-"
--D VERSION=\"$VERSION\"
--D MODULEDIR=\"$MODULEDIR\"
--D PREFIX=\"$PREFIX\"
--I src
--I lib
--I include
-"}
-
-export CFLAGS=${CFLAGS-"
---std=gnu99
--O0
--g
-"}
-
 NOLINK=1 sh build-aux/cc.sh lib/libc-gcc
 #NOLINK=1 sh build-aux/cc.sh lib/libc+tcc-gcc
 
diff --git a/build-aux/build-guile.sh b/build-aux/build-guile.sh
index 26ef74ed..73640807 100755
--- a/build-aux/build-guile.sh
+++ b/build-aux/build-guile.sh
@@ -20,7 +20,8 @@
 
 set -ex
 
-export GUILE=${GUILE-$(type -p guile)}
+export GUILE
+GUILE=${GUILE-$(command -v guile)}
 
 SCM_FILES="
 language/c99/compiler.scm
diff --git a/build-aux/build-mes.sh b/build-aux/build-mes.sh
index ee7c5f7c..36524bdd 100755
--- a/build-aux/build-mes.sh
+++ b/build-aux/build-mes.sh
@@ -18,27 +18,47 @@
 # You should have received a copy of the GNU General Public License
 # along with Mes.  If not, see <http://www.gnu.org/licenses/>.
 
-set -ex
+set -x
 
-export HEX2=${HEX2-hex2}
-export M1=${M1-M1}
-export BLOOD_ELF=${BLOOD_ELF-blood-elf}
-export MES_SEED=${MES_SEED-../mes-seed}
-export MESCC=${MESCC-$(type -p mescc)}
+export BLOOD_ELF GUILE HEX2 M1 MES MESCC
+export M1FLAGS HEX2FLAGS PREPROCESS
+export MES_SEED MES_ARENA
+
+HEX2=${HEX2-hex2}
+M1=${M1-M1}
+BLOOD_ELF=${BLOOD_ELF-blood-elf}
+MES_SEED=${MES_SEED-../mes-seed}
+MESCC=${MESCC-$(command -v mescc)}
 [ -z "$MESCC" ] && MESCC=scripts/mescc
-export MES=${MES-$(type -p mes)}
+MES=${MES-$(command -v mes)}
 [ -z "$MES" ] && MES=src/mes
 
+set -e
+
+M1FLAGS=${M1FLAGS-"
+--LittleEndian
+--Architecture=1
+"}
+HEX2FLAGS=${HEX2FLAGS-"
+--LittleEndian
+--Architecture=1
+--BaseAddress=0x1000000
+"}
+
 if [ -d "$MES_SEED" ]; then
-    $M1 --LittleEndian --Architecture=1\
+    $M1\
+        $M1FLAGS\
         -f stage0/x86.M1\
         -f $MES_SEED/crt1.M1\
         -o lib/crt1.hex2
-    $M1 --LittleEndian --Architecture=1\
+    $M1\
+        $M1FLAGS\
         -f stage0/x86.M1\
         -f $MES_SEED/libc-mes.M1\
         -o lib/libc-mes.hex2
-    $M1 --LittleEndian --Architecture=1\
+    $M1\
+        --LittleEndian\
+        --Architecture=1\
         -f stage0/x86.M1\
         -f $MES_SEED/mes.M1\
         -o src/mes.hex2
@@ -47,29 +67,33 @@ if [ -d "$MES_SEED" ]; then
         -f $MES_SEED/mes.M1\
         -f $MES_SEED/libc-mes.M1\
         -o src/mes.blood-elf.M1
-    $M1 --LittleEndian --Architecture=1\
+    $M1\
+        --LittleEndian\
+        --Architecture=1\
         -f src/mes.blood-elf.M1\
         -o src/mes.blood-elf.hex2
-    $HEX2 --LittleEndian --Architecture=1 --BaseAddress=0x1000000\
-          -f stage0/elf32-header.hex2\
-          -f lib/crt1.hex2\
-          -f lib/libc-mes.hex2\
-          -f src/mes.hex2\
-          -f src/mes.blood-elf.hex2\
-          --exec_enable\
-          -o src/mes.seed-out
+    $HEX2\
+        $HEX2FLAGS\
+        -f stage0/elf32-header.hex2\
+        -f lib/crt1.hex2\
+        -f lib/libc-mes.hex2\
+        -f src/mes.hex2\
+        -f src/mes.blood-elf.hex2\
+        --exec_enable\
+        -o src/mes.seed-out
     cp src/mes.seed-out src/mes
 
-    $M1 --LittleEndian --Architecture=1 -f\
-        stage0/x86.M1\
+    $M1\
+        $M1FLAGS\
+        -f stage0/x86.M1\
         -f $MES_SEED/libc+tcc-mes.M1\
         -o src/libc+tcc-mes.hex2
 fi
 
 [ -n "$SEED" ] && exit 0
 
-export GUILE=src/mes
-export MES_ARENA=${MES_ARENA-30000000}
+GUILE=src/mes
+MES_ARENA=${MES_ARENA-30000000}
 sh build-aux/mes-snarf.scm --mes src/gc.c
 sh build-aux/mes-snarf.scm --mes src/lib.c
 sh build-aux/mes-snarf.scm --mes src/math.c
@@ -78,7 +102,7 @@ sh build-aux/mes-snarf.scm --mes src/posix.c
 sh build-aux/mes-snarf.scm --mes src/reader.c
 sh build-aux/mes-snarf.scm --mes src/vector.c
 
-export PREPROCESS=1
+PREPROCESS=1
 NOLINK=1 sh build-aux/cc-mes.sh lib/crt1
 NOLINK=1 sh build-aux/cc-mes.sh lib/mini-libc-mes
 NOLINK=1 sh build-aux/cc-mes.sh lib/libc-mes
diff --git a/build-aux/build-mlibc.sh b/build-aux/build-mlibc.sh
index a6e40b18..9d10fb5e 100755
--- a/build-aux/build-mlibc.sh
+++ b/build-aux/build-mlibc.sh
@@ -20,7 +20,9 @@
 
 set -ex
 
-export CC32=${CC32-$(type -p i686-unknown-linux-gnu-gcc)}
+export CC32 CPPFLAGS C32FLAGS
+
+CC32=${CC32-$(command -v i686-unknown-linux-gnu-gcc)}
 build-aux/mes-snarf.scm --mes src/gc.c
 build-aux/mes-snarf.scm --mes src/lib.c
 build-aux/mes-snarf.scm --mes src/math.c
@@ -37,7 +39,7 @@ build-aux/mes-snarf.scm src/posix.c
 build-aux/mes-snarf.scm src/reader.c
 build-aux/mes-snarf.scm src/vector.c
 
-export CPPFLAGS=${CPPFLAGS-"
+CPPFLAGS=${CPPFLAGS-"
 -D VERSION=\"$VERSION\"
 -D MODULEDIR=\"$MODULEDIR\"
 -D PREFIX=\"$PREFIX\"
@@ -46,7 +48,7 @@ export CPPFLAGS=${CPPFLAGS-"
 -I include
 "}
 
-export C32FLAGS=${C32FLAGS-"
+C32FLAGS=${C32FLAGS-"
 --std=gnu99
 -O0
 -fno-stack-protector
diff --git a/build-aux/cc-mes.sh b/build-aux/cc-mes.sh
index 9c33e966..5836ddb6 100755
--- a/build-aux/cc-mes.sh
+++ b/build-aux/cc-mes.sh
@@ -18,15 +18,19 @@
 # You should have received a copy of the GNU General Public License
 # along with Mes.  If not, see <http://www.gnu.org/licenses/>.
 
-set -ex
+set -x
 
-export HEX2=${HEX2-hex2}
-export M1=${M1-M1}
-export BLOOD_ELF=${BLOOD_ELF-blood-elf}
-export MES_SEED=${MES_SEED-../mes-seed}
-export MESCC=${MESCC-$(type -p mescc)}
+export BLOOD_ELF GUILE HEX2 M1 MES MESCC
+export M1FLAGS HEX2FLAGS PREPROCESS
+export MES_SEED MES_ARENA
+
+HEX2=${HEX2-hex2}
+M1=${M1-M1}
+BLOOD_ELF=${BLOOD_ELF-blood-elf}
+MES_SEED=${MES_SEED-../mes-seed}
+MESCC=${MESCC-$(command -v mescc)}
 [ -z "$MESCC" ] && MESCC=scripts/mescc
-export MES=${MES-$(type -p mes)}
+MES=${MES-$(command -v mes)}
 [ -z "$MES" ] && MES=src/mes
 
 CPPFLAGS=${CPPFLAGS-"
@@ -41,9 +45,20 @@ CPPFLAGS=${CPPFLAGS-"
 MESCCLAGS=${MESCCFLAGS-"
 "}
 LIBC=${LIBC-lib/libc}
+M1FLAGS=${M1FLAGS-"
+--LittleEndian
+--Architecture=1
+"}
+HEX2FLAGS=${HEX2FLAGS-"
+--LittleEndian
+--Architecture=1
+--BaseAddress=0x1000000
+"}
 
 c=$1
 
+set -e
+
 if [ -n "$PREPROCESS" ]; then
     sh -x $MESCC\
        -E\
@@ -64,7 +79,8 @@ else
        "$c".c
 fi
 
-$M1 --LittleEndian --Architecture=1\
+$M1\
+    $M1FLAGS\
     -f stage0/x86.M1\
     -f "$c".M1\
     -o "$c".hex2
@@ -75,15 +91,17 @@ if [ -z "$NOLINK" ]; then
         -f "$c".M1\
         -f $LIBC-mes.M1\
         -o "$c".blood-elf-M1
-    $M1 --LittleEndian --Architecture=1\
+    $M1\
+        $M1FLAGS\
         -f "$c".blood-elf-M1\
         -o "$c".blood-elf-hex2
-    $HEX2 --LittleEndian --Architecture=1 --BaseAddress=0x1000000\
-          -f stage0/elf32-header.hex2\
-          -f lib/crt1.hex2\
-          -f $LIBC-mes.hex2\
-          -f "$c".hex2\
-          -f "$c".blood-elf-hex2\
-          --exec_enable\
-          -o "$c".mes-out
+    $HEX2\
+        $HEX2FLAGS\
+        -f stage0/elf32-header.hex2\
+        -f lib/crt1.hex2\
+        -f $LIBC-mes.hex2\
+        -f "$c".hex2\
+        -f "$c".blood-elf-hex2\
+        --exec_enable\
+        -o "$c".mes-out
 fi
diff --git a/build-aux/check-boot.sh b/build-aux/check-boot.sh
index 380611a0..f418c935 100755
--- a/build-aux/check-boot.sh
+++ b/build-aux/check-boot.sh
@@ -20,8 +20,9 @@
 
 set -e
 
-export GUILE=${GUILE-guile}
-export MES=${MES-./src/mes}
+export GUILE MES
+GUILE=${GUILE-guile}
+MES=${MES-./src/mes}
 
 tests="
 
diff --git a/build-aux/check-mescc.sh b/build-aux/check-mescc.sh
index 0eb15690..3c87e715 100755
--- a/build-aux/check-mescc.sh
+++ b/build-aux/check-mescc.sh
@@ -18,18 +18,22 @@
 # You should have received a copy of the GNU General Public License
 # along with Mes.  If not, see <http://www.gnu.org/licenses/>.
 
-export MES=${MES-src/mes}
-export MESCC=${MESCC-scripts/mescc}
-export GUILE=${GUILE-guile}
-export MES_PREFIX=${MES_PREFIX-.}
+export BLOOD_ELF GUILE HEX2 M1 MES MESCC
+export M1FLAGS HEX2FLAGS PREPROCESS LIBC
+export MES_ARENA MES_PREFIX MES_SEED
 
-export HEX2=${HEX2-hex2}
-export M1=${M1-M1}
-export BLOOD_ELF=${BLOOD_ELF-blood-elf}
-export MES_SEED=${MES_SEED-../mes-seed}
-export MESCC=${MESCC-$(type -p mescc)}
+MES=${MES-src/mes}
+MESCC=${MESCC-scripts/mescc}
+GUILE=${GUILE-guile}
+MES_PREFIX=${MES_PREFIX-.}
+
+HEX2=${HEX2-hex2}
+M1=${M1-M1}
+BLOOD_ELF=${BLOOD_ELF-blood-elf}
+MES_SEED=${MES_SEED-../mes-seed}
+MESCC=${MESCC-$(command -v mescc)}
 [ -z "$MESCC" ] && MESCC=scripts/mescc
-export MES=${MES-$(type -p mes)}
+MES=${MES-$(command -v mes)}
 [ -z "$MES" ] && MES=src/mes
 
 
@@ -115,7 +119,7 @@ expect=$(echo $broken | wc -w)
 pass=0
 fail=0
 total=0
-export LIBC=libc/libc
+LIBC=libc/libc
 for t in $tests; do
     if [ -z "${t/[012][0-9]-*/}" ]; then
         LIBC=lib/mini-libc;
diff --git a/build-aux/test.sh b/build-aux/test.sh
index cf9932a7..af01c6c4 100755
--- a/build-aux/test.sh
+++ b/build-aux/test.sh
@@ -18,16 +18,19 @@
 # You should have received a copy of the GNU General Public License
 # along with Mes.  If not, see <http://www.gnu.org/licenses/>.
 
-set -ex
+set -x
 
 GUILE=${GUILE-$MES}
 DIFF=${DIFF-$(command -v diff)}
-DIFF=${DIFF-sh build-aux/diff.scm}
+[ -z "$DIFF" ] && DIFF="sh build-aux/diff.scm"
 
 t=${1-scaffold/tests/t}
-#rm -f "$t".i686-unknown-linux-gnu-out
 rm -f "$t".mes-out
+shift
 
+set -e
+
+rm -f "$t".mes-out
 sh build-aux/cc-mes.sh "$t"
 
 r=0
diff --git a/build.sh b/build.sh
index df558c07..2e2525ea 100755
--- a/build.sh
+++ b/build.sh
@@ -18,20 +18,59 @@
 # You should have received a copy of the GNU General Public License
 # along with Mes.  If not, see <http://www.gnu.org/licenses/>.
 
-set -ex
+set -x
+# dash does not export foo=${foo-bar} for some values
+export CC CC32 GUILE MESCC MES_SEED
+export MES_ARENA MES_DEBUG
+export PREFIX DATADIR MODULEDIR
+export CPPFLAGS CFLAGS C32FLAGS MESCCFLAGS
 
-export CC=${CC-$(type -p gcc)}
-export CC32=${CC32-$(type -p i686-unknown-linux-gnu-gcc)}
-export MESCC=${MESCC-$(type -p mescc)}
-export MES_SEED=${MES_SEED-../mes-seed}
-export GUILE=${GUILE-$(type -p guile)}
-export MES_ARENA=${MES_ARENA-300000000}
-export MES_DEBUG=${MES_DEBUG-2}
+CC=${CC-$(command -v gcc)}
+CC32=${CC32-$(command -v i686-unknown-linux-gnu-gcc)}
+MESCC=${MESCC-$(command -v mescc)}
+MES_SEED=${MES_SEED-../mes-seed}
+GUILE=${GUILE-$(command -v guile)}
+MES_ARENA=${MES_ARENA-300000000}
+MES_DEBUG=${MES_DEBUG-2}
 
-export PREFIX=${PREFIX-/usr/local}
-export DATADIR=${DATADIR-$PREFIX/share/mes}
-export MODULEDIR=${MODULEDIR-$DATADIR/module}
+PREFIX=${PREFIX-/usr/local}
+DATADIR=${DATADIR-$PREFIX/share/mes}
+MODULEDIR=${MODULEDIR-$DATADIR/module}
+set -e
 
+CPPFLAGS=${CPPFLAGS-"
+-D VERSION=\"$VERSION\"
+-D MODULEDIR=\"$MODULEDIR\"
+-D PREFIX=\"$PREFIX\"
+-I src
+-I lib
+-I include
+"}
+CFLAGS=${CFLAGS-"
+--std=gnu99
+-O0
+-g
+"}
+C32FLAGS=${C32FLAGS-"
+--std=gnu99
+-O0
+-fno-stack-protector
+-g
+-m32
+-nostdinc
+-nostdlib
+"}
+MESCCLAGS=${MESCCFLAGS-"
+"}
+M1FLAGS=${M1FLAGS-"
+--LittleEndian
+--Architecture=1
+"}
+HEX2FLAGS=${HEX2FLAGS-"
+--LittleEndian
+--Architecture=1
+--BaseAddress=0x1000000
+"}
 
 if [ -n "$GUILE" ]; then
     sh build-aux/build-guile.sh
diff --git a/check.sh b/check.sh
index 9636c0c3..1eecadf9 100755
--- a/check.sh
+++ b/check.sh
@@ -18,9 +18,10 @@
 # You should have received a copy of the GNU General Public License
 # along with Mes.  If not, see <http://www.gnu.org/licenses/>.
 
-export GUILE=${GUILE-guile}
-export MES=${MES-src/mes}
-export MES_ARENA=${MES_ARENA-100000000}
+export GUILE MES MES_ARENA
+GUILE=${GUILE-guile}
+MES=${MES-src/mes}
+MES_ARENA=${MES_ARENA-100000000}
 
 set -e
 bash build-aux/check-boot.sh
diff --git a/configure b/configure
index dc802c18..2a5f8619 100755
--- a/configure
+++ b/configure
@@ -2,7 +2,7 @@
 # -*- scheme -*-
 unset LANG LC_ALL
 echo -n "checking for guile..."
-GUILE=$(type -p ${GUILE-guile} 2>/dev/null|tail -n 1|sed 's,^.* ,,')
+GUILE=$(command -v ${GUILE-guile} 2>/dev/null|tail -n 1|sed 's,^.* ,,')
 export GUILE
 if [ -x "$GUILE" ]; then
     echo " $GUILE"
@@ -175,6 +175,11 @@ exec ${GUILE} --no-auto-compile -L $(pwd) -C $(pwd) -e 'main' -s "$0" ${1+"$@"}
                      "i686-unknown-linux-gnu-gcc")))
 (define HEX2 (or (getenv "HEX2") "hex2"))
 (define M1 (or (getenv "M1") "M1"))
+(define CFLAGS (getenv "CFLAGS"))
+(define C32FLAGS (getenv "C32FLAGS"))
+(define HEX2FLAGS (getenv "HEX2FLAGS"))
+(define M1FLAGS (getenv "M1FLAGS"))
+(define MESCCFLAGS (getenv "MESCCFLAGS"))
 
 (define (parse-opts args)
   (let* ((option-spec
@@ -261,10 +266,15 @@ Usage: ./configure [OPTION]...
         (stdout "PACKAGE:=~a\n" PACKAGE)
         (stdout "VERSION:=~a\n" VERSION)
         (stdout "PREFIX:=~a\n" (gulp-pipe (string-append "echo " prefix)))
-        (stdout "SYSCONFDIR:=~a\n" sysconfdir)))
+        (stdout "SYSCONFDIR:=~a\n" sysconfdir)
+        (when CFLAGS (stdout "CFLAGS:=~a\n" CFLAGS))
+        (when C32FLAGS (stdout "C32FLAGS:=~a\n" C32FLAGS))
+        (when HEX2FLAGS (stdout "HEX2FLAGS:=~a\n" HEX2FLAGS))
+        (when M1FLAGS (stdout "M1FLAGS:=~a\n" M1FLAGS))
+        (when MESCCFLAGS (stdout "MESCCFLAGS:=~a\n" MESCCFLAGS))))
     (format (current-output-port)
             "\nRun:
   ~a            to build mes
   ~a help       for help on other targets\n"
-            (if make? "make" "./make.scm")
-            (if make? "make" "./make.scm"))))
+            (if make? "make" "./build.sh")
+            (if make? "make" "./build.sh"))))
diff --git a/install.sh b/install.sh
index 1c80a8b8..b3036ab0 100755
--- a/install.sh
+++ b/install.sh
@@ -2,7 +2,8 @@
 
 set -e
 
-export PREFIX=${PREFIX-/usr/local}
+export PREFIX
+PREFIX=${PREFIX-/usr/local}
 MES_PREFIX=${MES_PREFIX-$PREFIX/share/mes}
 MES_SEED=${MES_SEED-../mes-seed}
 TINYCC_SEED=${TINYCC_SEED-../tinycc-seed}
diff --git a/scripts/mescc b/scripts/mescc
index b37de93f..4baf7cc5 100755
--- a/scripts/mescc
+++ b/scripts/mescc
@@ -1,6 +1,6 @@
 #! /bin/sh
 # -*-scheme-*-
-mes_p=$(type -p mes)
+mes_p=$(command -v mes)
 if [ '(' -z "$mes_p" -a -z "$MES" ')' -o "$MES" = "guile" -o "$MES" = "mes.guile" ]; then
     GODIR=${GODIR-@GODIR@}
     GUILEDIR=${GUILEDIR-@GUILEDIR@}