diff --git a/install.sh b/install.sh
index 102fc00c..f8b24e18 100755
--- a/install.sh
+++ b/install.sh
@@ -29,7 +29,7 @@ DOCDIR=${MODULEDIR-$PREFIX/share/doc/mes}
 
 chmod +w $PREFIX/bin/mescc
 sed \
-    -e "s,^#! /bin/sh,#! $SHELL/," \
+    -e "s,^#! /bin/sh,#! $SHELL," \
     -e "s,module/,$MODULEDIR/," \
     -e "s,@DATADIR@,$DATADIR,g" \
     -e "s,@DOCDIR@,$DOCDIR,g" \
@@ -41,7 +41,7 @@ sed \
     scripts/mescc > $PREFIX/bin/mescc
 chmod +w $MODULEDIR/mes/boot-0.scm
 sed \
-    -e "s,^#! /bin/sh,#! $SHELL/," \
+    -e "s,^#! /bin/sh,#! $SHELL," \
     -e "s,module/,$MODULEDIR/," \
     -e "s,@DATADIR@,$DATADIR,g" \
     -e "s,@DOCDIR@,$DOCDIR,g" \
@@ -54,5 +54,5 @@ sed \
 
 cp scripts/diff.scm $PREFIX/bin/diff.scm
 sed \
-    -e "s,^#! /bin/sh,#! $SHELL/," \
+    -e "s,^#! /bin/sh,#! $SHELL," \
     scripts/diff.scm > $PREFIX/bin/diff.scm
diff --git a/scripts/diff.scm b/scripts/diff.scm
index 74eef112..1ce3492a 100755
--- a/scripts/diff.scm
+++ b/scripts/diff.scm
@@ -4,7 +4,7 @@ mes_p=$(command -v mes)
 if [ "$mes_p" -a -z "$MES" ]; then
     MES=guile
 fi
-exec ${MES-mes} -L $(dirname 0) -e '(diff)' -s "$0" "$@"
+exec ${MES-mes} -L ${0%/*} -e '(diff)' -s "$0" "$@"
 !#
 
 ;;; Mes --- Maxwell Equations of Software