diff --git a/test/installer.sh b/test/installer.sh
index d3f747c8310..04c3c80c212 100644
--- a/test/installer.sh
+++ b/test/installer.sh
@@ -129,4 +129,4 @@ echo "$targetDevice / somefs rw 0 0" > $mountPoint/etc/mtab
 # a menu default pointing at the kernel/initrd/etc of the new
 # configuration.
 echo "finalising the installation..."
-chroot $mountPoint /nix/var/nix/profiles/system/bin/switch-to-configuration
+NIXOS_INSTALL_GRUB=1 chroot $mountPoint /nix/var/nix/profiles/system/bin/switch-to-configuration
diff --git a/test/system-configuration.sh b/test/system-configuration.sh
index 11254a24d0a..a9351f97ade 100644
--- a/test/system-configuration.sh
+++ b/test/system-configuration.sh
@@ -19,7 +19,9 @@ export PATH=$coreutils/bin:$gnused/bin:$gnugrep/bin:$diffutils/bin
 if test -n "$grubDevice"; then
     mkdir -m 0700 -p /boot/grub
     $grubMenuBuilder $out
-    $grub/sbin/grub-install "$grubDevice" --no-floppy --recheck
+    if test "\$NIXOS_INSTALL_GRUB" = 1; then
+        $grub/sbin/grub-install "$grubDevice" --no-floppy --recheck
+    fi
 fi
 EOF