diff --git a/make-disk.sh b/make-disk.sh
index fc62a697deaa..6043b61fcb20 100755
--- a/make-disk.sh
+++ b/make-disk.sh
@@ -3,7 +3,13 @@
 # deps is an array
 declare -a deps
 
-archivesDir=$(mktemp -d)
+# determine where we can find the Nix binaries
+NIX=$(dirname $(which nix-store))
+
+# make sure we use our own mktemp, because it is more pure
+mktemp=$($NIX/nix-store -r $(echo '(import ./pkgs.nix).mktemp' | $NIX/nix-instantiate -))
+archivesDir=$($mktemp/bin/mktemp -d)
+
 manifest=${archivesDir}/MANIFEST
 nixpkgs=/nixpkgs/trunk/pkgs
 fill_disk=$archivesDir/scripts/fill-disk.sh
@@ -15,8 +21,6 @@ initrd=/tmp/initram.img
 initdir=${archivesDir}/initdir
 initscript=$archivesDir/scripts/init.sh
 
-# determine where we can find the Nix binaries
-NIX=$(dirname $(which nix-store))
 
 storeExpr=$($NIX/nix-store -qR $($NIX/nix-store -r $(echo '(import ./pkgs.nix).everything' | $NIX/nix-instantiate -)))
 #$NIX/nix-push --copy $archivesDir $manifest $($NIX/nix-store -r $storeExpr) $($NIX/nix-store -r $(echo '(import ./pkgs.nix).kernel' | $NIX/nix-instantiate -))
diff --git a/pkgs.nix b/pkgs.nix
index f028a8e03d3a..66076370bc37 100644
--- a/pkgs.nix
+++ b/pkgs.nix
@@ -5,7 +5,7 @@ rec {
     nettools nixUnstable subversion gcc wget which vim less screen openssh binutils
     strace shadowutils iputils gnumake curl gnused gnutar gnugrep gzip
     mingettyWrapper grubWrapper syslinux parted module_init_tools module_init_toolsStatic udev
-    dhcpWrapper man nano eject sysklogd kudzu xawtv;
+    dhcpWrapper man nano eject sysklogd kudzu xawtv mktemp;
 
   boot = (import ./boot) {inherit stdenv bash bashStatic coreutils findutilsWrapper
     utillinux utillinuxStatic sysvinit e2fsprogs nettools subversion gcc wget which vim