diff --git a/helpers/make-iso9660-image.sh b/helpers/make-iso9660-image.sh
index 03f4208375c7..5ba133b6890d 100644
--- a/helpers/make-iso9660-image.sh
+++ b/helpers/make-iso9660-image.sh
@@ -42,9 +42,6 @@ done
 printRegistration=1 perl $pathsFromGraph closure-* > nix-path-registration
 echo "nix-path-registration=nix-path-registration" >> pathlist
 
-printManifest=1 perl $pathsFromGraph closure-* > MANIFEST
-echo "MANIFEST=MANIFEST" >> pathlist
-
 
 # Add symlinks to the top-level store objects.
 for ((n = 0; n < ${#objects[*]}; n++)); do
diff --git a/installer/cd-dvd/rescue-cd.nix b/installer/cd-dvd/rescue-cd.nix
index 427d21e523c6..c34fc259340e 100644
--- a/installer/cd-dvd/rescue-cd.nix
+++ b/installer/cd-dvd/rescue-cd.nix
@@ -60,6 +60,9 @@ rec {
           # Firewire support.  Not tested.
           "ohci1394" "sbp2"
 
+          # Virtio (QEMU, KVM etc.) support.
+          "virtio_net" "virtio_pci" "virtio_blk" "virtio_balloon"
+
           # Wait for SCSI devices to appear.
           "scsi_wait_scan"
 
diff --git a/installer/nixos-install.sh b/installer/nixos-install.sh
index 44fdf2d3337a..1288304cbe0f 100644
--- a/installer/nixos-install.sh
+++ b/installer/nixos-install.sh
@@ -101,6 +101,7 @@ mkdir -m 1777 -p \
 # Get the store paths to copy from the references graph.
 storePaths=$(@perl@/bin/perl @pathsFromGraph@ @nixClosure@)
 
+
 # Copy Nix to the Nix store on the target device.
 echo "copying Nix to $mountPoint...."
 for i in $storePaths; do
@@ -124,15 +125,9 @@ mkdir -m 0755 -p $mountPoint/bin
 ln -sf @shell@ $mountPoint/bin/sh
 
 
-# Pull the manifest on the CD so that everything in the Nix store on
-# the CD can be copied directly.
-echo "registering substitutes to speed up builds..."
-rm -f $mountPoint/nix/var/nix/manifests/*
-if test -e /MANIFEST; then
-    chroot $mountPoint @nix@/bin/nix-pull file:///mnt/MANIFEST
-fi
-rm -f $mountPoint/tmp/inst-store
-ln -s /mnt/nix/store $mountPoint/tmp/inst-store
+# Make the build below copy paths from the CD if possible.  Note that
+# /mnt in the chroot is the root of the CD.
+export NIX_OTHER_STORES=/mnt/nix:$NIX_OTHER_STORES
 
 
 # Do a nix-pull to speed up building.
diff --git a/system/switch-to-configuration.sh b/system/switch-to-configuration.sh
index ef1893880e2d..593dd61714e7 100644
--- a/system/switch-to-configuration.sh
+++ b/system/switch-to-configuration.sh
@@ -29,7 +29,7 @@ if test "$action" = "switch" -o "$action" = "boot"; then
             @grub@/sbin/grub-install "@grubDevice@" --no-floppy --recheck
         fi
     else
-        echo "Warning: don't know how to make this configuration bootable" 1>&2
+        echo "Warning: don't know how to make this configuration bootable; please set \`boot.grubDevice'." 1>&2
     fi
 fi