diff --git a/guix-vm-installer.xml b/guix-vm-installer.xml
index 4d6110d..7c0b74f 100644
--- a/guix-vm-installer.xml
+++ b/guix-vm-installer.xml
@@ -1,7 +1,7 @@
 <domain type="kvm">
   <name>guix-vm-installer</name>
-  <memory unit="KiB">16777216</memory>
-  <currentMemory unit="KiB">16777216</currentMemory>
+  <memory unit="KiB">4194304</memory>
+  <currentMemory unit="KiB">4194304</currentMemory>
   <resource>
     <partition>/machine</partition>
   </resource>
diff --git a/mumble-vm-install.sh b/mumble-vm-install.sh
index fcb274d..921c792 100755
--- a/mumble-vm-install.sh
+++ b/mumble-vm-install.sh
@@ -207,15 +207,30 @@ guix shell -C --nesting autoconf automake bash coreutils grep sed -- \
 guix shell -C --nesting bash coreutils gawk grep sed -- \
      ./configure ; report "./configure"
 
-# TODO: use guix init or temporary storage instead to reduce the
-# memory consumption. Right now we tested this script with 16GiB of
-# RAM which is probably too big for many potential users. Requiring
-# 4GiB would be more reasonable.
-guix shell -C --nesting automake coreutils gawk grep make sed -- \
-     make ; report "make"
+guix shell -C --nesting automake coreutils gawk grep make sed tar xz -- \
+     make mumble-vm.tar.xz ; report "Generating VM definition"
 
-guix shell -C ddrescue -- ddrescue mumble-vm.img /dev/vda && sync ; \
-    report "ddrescue mumble-vm.img /dev/vda"
+cp mumble-vm.tar.xz ../ && \
+    cd ../ && \
+    rm -rf mumble-vm && \
+    guix shell -C tar xz -- tar xf mumble-vm.tar.xz && \
+    rm -f mumble-vm.tar.xz ; report "Removing git repository"
+
+guix gc ; report "guix gc"
+
+echo 'label: gpt' | sfdisk /dev/vda ; report "GPT creation on /dev/vda" ; \
+    report "GPT formating"
+
+echo ';;L;*' | sfdisk /dev/vda  ; report "/dev/vda1 creation" ; \
+    report "Adding partition"
+
+mkfs.ext4 -F -L Guix_image /dev/vda1 ; report "EXT4 formating"
+
+mount /dev/vda1 /mnt ; report "mount /dev/vda1 /mnt" ; report "mounting rootfs"
+
+herd start cow-store /mnt ; report "Using /mnt for storing guix system init packages"
+guix system init mumble-vm-system.scm /mnt ; report "guix system init"
+umount /mnt ; report "umount rootfs"
 
 printf "Installation done: %s\n" \
        "you can remove the install media and reboot to the new VM"