diff --git a/test/boot-stage-1-init.sh b/test/boot-stage-1-init.sh
index a5957fada5f..f216f05e237 100644
--- a/test/boot-stage-1-init.sh
+++ b/test/boot-stage-1-init.sh
@@ -26,7 +26,7 @@ mount -t sysfs sys /sys
 source @makeDevices@
 
 # Load some kernel modules.
-export MODULE_DIR=@kernel@/lib/modules/
+export MODULE_DIR=@modules@/lib/modules/
 modprobe ide-generic
 modprobe ide-disk
 modprobe ide-cd
diff --git a/test/boot-stage-1.nix b/test/boot-stage-1.nix
index 9fed0020c76..1099fe08a21 100644
--- a/test/boot-stage-1.nix
+++ b/test/boot-stage-1.nix
@@ -5,17 +5,17 @@
 # is supposed to be put into an initial RAM disk (initrd).
 
 { genericSubstituter, shell, staticTools
-, module_init_tools, utillinux, kernel
+, module_init_tools, utillinux, modules
 }:
 
 genericSubstituter {
   src = ./boot-stage-1-init.sh;
   isExecutable = true;
-  inherit shell kernel;
+  inherit shell modules;
   path = [
     staticTools
     module_init_tools
-    utillinux
+#    utillinux
   ];
   makeDevices = ./make-devices.sh;
 }
diff --git a/test/modules-closure.nix b/test/modules-closure.nix
new file mode 100644
index 00000000000..86015a8b182
--- /dev/null
+++ b/test/modules-closure.nix
@@ -0,0 +1,13 @@
+# Given a kernel build (with modules in $kernel/lib/modules/VERSION),
+# produce a module tree in $out/lib/modules/VERSION that contains only
+# the modules identified by `rootModules', plus their dependencies.
+# Also generate an appropriate modules.dep.
+
+{stdenv, kernel, rootModules, module_init_tools}:
+
+stdenv.mkDerivation {
+  name = kernel.name + "-shrunk";
+  builder = ./modules-closure.sh;
+  inherit kernel rootModules module_init_tools;
+  allowedReferences = ["out"];
+}
diff --git a/test/modules-closure.sh b/test/modules-closure.sh
new file mode 100644
index 00000000000..c5fcbba87f1
--- /dev/null
+++ b/test/modules-closure.sh
@@ -0,0 +1,37 @@
+source $stdenv/setup
+
+set -o pipefail
+
+PATH=$module_init_tools/sbin:$PATH
+
+version=$(cd $kernel/lib/modules && ls -d *)
+
+echo "kernel version is $version"
+
+export MODULE_DIR=$kernel/lib/modules/
+
+# Determine the dependencies of each root module.
+closure=
+for module in $rootModules; do
+    echo "root module: $module"
+    deps=$(modprobe --set-version "$version" --show-depends "$module" \
+        | sed 's/^insmod //')
+    for i in $deps; do echo $i; done
+    closure="$closure $deps"
+done
+
+# Remove duplicates.
+closure=$(for i in $closure; do echo $i; done | sort | uniq)
+
+echo "closure:"
+ensureDir $out
+for module in $closure; do
+    echo $module
+    target=$(echo $module | sed "s^$kernel^$out^")
+    mkdir -p $(dirname $target)
+    cp $module $target
+    grep "^$module" $kernel/lib/modules/$version/modules.dep \
+        | sed "s^$kernel^$out^g" \
+        >> $out/lib/modules/$version/modules.dep
+done
+
diff --git a/test/rescue-system.nix b/test/rescue-system.nix
index 9491e8538e5..b42030b659c 100644
--- a/test/rescue-system.nix
+++ b/test/rescue-system.nix
@@ -11,21 +11,20 @@ rec {
     allPackages = import ./pkgs/top-level/all-packages.nix;
   };
 
-  bash = pkgs.bash;
-
 
   # Determine the set of modules that we need to mount the root FS.
   modulesClosure = import ./modules-closure.nix {
-    inherit (pkgs) stdenv kernel;
-    rootModules = "ide-cd";
+    inherit (pkgs) stdenv kernel module_init_tools;
+    rootModules = ["ide-cd" "ide-disk" "ide-generic"];
   };
 
 
   # The init script of boot stage 1 (loading kernel modules for
   # mounting the root FS).
   bootStage1 = import ./boot-stage-1.nix {
-    inherit (pkgs) genericSubstituter
-      module_init_tools utillinux kernel;
+    inherit (pkgs) genericSubstituter utillinux;
+    inherit (pkgsDiet) module_init_tools;
+    modules = modulesClosure;
     shell = stdenvLinuxStuff.bootstrapTools.bash;
     staticTools = stdenvLinuxStuff.staticTools;
   };