diff --git a/preseed/Makefile b/preseed/Makefile
index c2bc121..fb87988 100644
--- a/preseed/Makefile
+++ b/preseed/Makefile
@@ -13,36 +13,24 @@
 # You should have received a copy of the GNU General Public License
 # along with this project.  If not, see <http://www.gnu.org/licenses/>.
 
+GUIX_VERSION ?= v1.4.0
+GUIX_SHELL ?= guix time-machine --commit=$(GUIX_VERSION) -- shell
+
 .PHONY: mtools-signkey
 
 all: preseed.img check
 
-pubring.kbx:
-	gpg --homedir $$PWD \
-		--list-keys 51A23D9D7C4DF41AA48FA893E99CF5537790B839 || \
-	gpg --homedir $$PWD \
-		--recv-keys 51A23D9D7C4DF41AA48FA893E99CF5537790B839
+PRESEED_IMG_DEPS = \
+	Makefile \
+	../trisquel-guix-installer.experimental.a-lec.org/config/debconf/FAIBASE
 
-mtools-4.0.43.tar.bz2:
-	wget http://ftp.gnu.org/gnu/mtools/$@ -O $@
-
-mtools-4.0.43.tar.bz2.sig:
-	wget http://ftp.gnu.org/gnu/mtools/$@ -O $@
-
-mtools-4.0.43: mtools-4.0.43.tar.bz2 mtools-4.0.43.tar.bz2.sig
-	gpg --homedir $$PWD --verify mtools-4.0.43.tar.bz2.sig
-	tar xf mtools-4.0.43.tar.bz2
-	cd mtools-4.0.43 && \
-		./configure && \
-		make
-
-preseed.img: mtools-4.0.43
+preseed.img: $(PRESEED_IMG_DEPS)
 	dd if=/dev/zero of=$@ count=2048
-	mtools-4.0.43/mformat -i $@ ::
-	mtools-4.0.43/mcopy   -i $@ \
+	$(GUIX_SHELL) mtools -- mformat -i $@ ::
+	$(GUIX_SHELL) mtools -- mcopy   -i $@ \
 	../trisquel-guix-installer.experimental.a-lec.org/config/debconf/FAIBASE \
 	::
-	mtools-4.0.43/mdir -i $@ ::
+	$(GUIX_SHELL) mtools -- mdir -i $@ ::
 
 check: preseed.img preseed.img.sha512
 	sha512sum -c preseed.img.sha512
diff --git a/preseed/preseed.img.sha512 b/preseed/preseed.img.sha512
index aae4cd5..a430da5 100644
--- a/preseed/preseed.img.sha512
+++ b/preseed/preseed.img.sha512
@@ -1 +1 @@
-7a3b97468a3782f3fd28cf9bf6b96d79b6ef2c31d4a45c19abf776fc944b27ba78469ec72d991c8e97e50641c7adc8fd5cf86b798f47bbfe07ed41dedae9fcff  preseed.img
+4ccceabb06d01526915c15a4f5b5dab58d75f3dc70ad4837696e29d9dc1956f4a5652f2a0574602fc12fa42b34e11df69fa0cc3da87e6eff8d7a18d50a16ae07  preseed.img