diff --git a/system/activate-configuration.sh b/system/activate-configuration.sh
index addeeb2f8208..d7360f274863 100644
--- a/system/activate-configuration.sh
+++ b/system/activate-configuration.sh
@@ -36,6 +36,14 @@ mkdir -m 0755 -p $mountPoint/bin
 ln -sfn @shell@ $mountPoint/bin/sh
 
 
+# Allow the kernel to find our wrapped modprobe (which searches in the
+# right location in the Nix store for kernel modules).  We need this
+# when the kernel (or some module) auto-loads a module.
+# !!! maybe this should only happen at boot time, since we shouldn't
+# use modules that don't match the running kernel.
+echo @modprobe@/sbin/modprobe > /proc/sys/kernel/modprobe
+
+
 # Various log directories.
 mkdir -m 0755 -p /var/run
 
diff --git a/system/modprobe b/system/modprobe
new file mode 100644
index 000000000000..5971880f0648
--- /dev/null
+++ b/system/modprobe
@@ -0,0 +1,3 @@
+#! @shell@
+export MODULE_DIR=@kernel@/lib/modules
+exec @module_init_tools@/sbin/modprobe "$@"
diff --git a/system/system.nix b/system/system.nix
index e032bad07ab3..03ec3b1c3a4c 100644
--- a/system/system.nix
+++ b/system/system.nix
@@ -131,9 +131,18 @@ rec {
     (map (mod: mod + "/lib") nssModules));
 
 
+  # Wrapper around modprobe to set the path to the modules.
+  modprobe = pkgs.substituteAll {
+    dir = "sbin";
+    src = ./modprobe;
+    isExecutable = true;
+    inherit (pkgs) kernel module_init_tools;
+  };
+
+
   # The services (Upstart) configuration for the system.
   upstartJobs = import ./upstart.nix {
-    inherit config pkgs nix nssModulesPath;
+    inherit config pkgs nix modprobe nssModulesPath;
   };
 
 
@@ -155,6 +164,7 @@ rec {
 
   # The packages you want in the boot environment.
   systemPathList = [
+    modprobe # must take precedence over module_init_tools
     pkgs.bash
     pkgs.bzip2
     pkgs.coreutils
@@ -220,7 +230,7 @@ rec {
     src = ./activate-configuration.sh;
     isExecutable = true;
 
-    inherit etc wrapperDir systemPath;
+    inherit etc wrapperDir systemPath modprobe;
     inherit (pkgs) kernel;
     readOnlyRoot = config.get ["boot" "readOnlyRoot"];
     hostName = config.get ["networking" "hostName"];
diff --git a/system/upstart.nix b/system/upstart.nix
index fc694eefc133..eb185a2b204b 100644
--- a/system/upstart.nix
+++ b/system/upstart.nix
@@ -1,4 +1,4 @@
-{config, pkgs, nix, nssModulesPath}:
+{config, pkgs, nix, modprobe, nssModulesPath}:
 
 let 
 
@@ -31,17 +31,19 @@ import ../upstart-jobs/gather.nix {
       
     # Makes LVM logical volumes available. 
     (import ../upstart-jobs/lvm.nix {
-      inherit (pkgs) kernel module_init_tools lvm2;
+      inherit modprobe;
+      inherit (pkgs) lvm2;
     })
       
     # Activate software RAID arrays.
     (import ../upstart-jobs/swraid.nix {
-      inherit (pkgs) kernel module_init_tools mdadm;
+      inherit modprobe;
+      inherit (pkgs) mdadm;
     })
       
     # Hardware scan; loads modules for PCI devices.
     (import ../upstart-jobs/hardware-scan.nix {
-      inherit (pkgs) kernel module_init_tools;
+      inherit modprobe;
       doHardwareScan = config.get ["boot" "hardwareScan"];
       kernelModules = config.get ["boot" "kernelModules"];
     })
@@ -60,7 +62,8 @@ import ../upstart-jobs/gather.nix {
 
     # Network interfaces.
     (import ../upstart-jobs/network-interfaces.nix {
-      inherit (pkgs) nettools kernel module_init_tools wirelesstools;
+      inherit modprobe;
+      inherit (pkgs) nettools wirelesstools;
       nameservers = config.get ["networking" "nameservers"];
       defaultGateway = config.get ["networking" "defaultGateway"];
       interfaces = config.get ["networking" "interfaces"];
@@ -113,7 +116,8 @@ import ../upstart-jobs/gather.nix {
   # NTP daemon.
   ++ optional ["services" "ntp" "enable"]
     (import ../upstart-jobs/ntpd.nix {
-      inherit (pkgs) ntp kernel module_init_tools glibc pwdutils writeText;
+      inherit modprobe;
+      inherit (pkgs) ntp glibc pwdutils writeText;
       servers = config.get ["services" "ntp" "servers"];
     })
 
@@ -136,7 +140,8 @@ import ../upstart-jobs/gather.nix {
   # ALSA sound support.
   ++ optional ["sound" "enable"]
     (import ../upstart-jobs/alsa.nix {
-      inherit (pkgs) kernel module_init_tools alsaUtils;
+      inherit modprobe;
+      inherit (pkgs) alsaUtils;
     })
 
   # Handles the reboot/halt events.
diff --git a/upstart-jobs/alsa.nix b/upstart-jobs/alsa.nix
index de258a8770b1..1b018b2259a8 100644
--- a/upstart-jobs/alsa.nix
+++ b/upstart-jobs/alsa.nix
@@ -1,4 +1,4 @@
-{kernel, module_init_tools, alsaUtils}:
+{modprobe, alsaUtils}:
 
 let
 
@@ -16,9 +16,8 @@ stop on shutdown
 start script
 
     # Load some additional modules.
-    export MODULE_DIR=${kernel}/lib/modules/
     for mod in snd_pcm_oss; do
-        ${module_init_tools}/sbin/modprobe $mod || true
+        ${modprobe}/sbin/modprobe $mod || true
     done
 
     # Restore the sound state.
diff --git a/upstart-jobs/hardware-scan.nix b/upstart-jobs/hardware-scan.nix
index 6cca5f7562f5..80b7f440b76d 100644
--- a/upstart-jobs/hardware-scan.nix
+++ b/upstart-jobs/hardware-scan.nix
@@ -1,5 +1,4 @@
-# !!! Don't like it that I have to pass the kernel here.
-{kernel, module_init_tools, doHardwareScan, kernelModules}:
+{modprobe, doHardwareScan, kernelModules}:
 
 {
   name = "hardware-scan";
@@ -8,11 +7,9 @@
 start on udev
 
 script
-    export MODULE_DIR=${kernel}/lib/modules/
-
     for i in ${toString kernelModules}; do
         echo \"Loading kernel module $i...\"
-        ${module_init_tools}/sbin/modprobe $i || true
+        ${modprobe}/sbin/modprobe $i || true
     done
 
     if test -n \"${toString doHardwareScan}\" -a ! -e /var/run/safemode; then
@@ -20,7 +17,7 @@ script
         # Try to load modules for all PCI devices.
         for i in /sys/bus/pci/devices/*/modalias; do
             echo \"Trying to load a module for $(basename $(dirname $i))...\"
-            ${module_init_tools}/sbin/modprobe $(cat $i) || true
+            ${modprobe}/sbin/modprobe $(cat $i) || true
             echo \"\"
         done
 
diff --git a/upstart-jobs/lvm.nix b/upstart-jobs/lvm.nix
index 558b80cd6514..ee6e842564c3 100644
--- a/upstart-jobs/lvm.nix
+++ b/upstart-jobs/lvm.nix
@@ -1,4 +1,4 @@
-{kernel, module_init_tools, lvm2}:
+{modprobe, lvm2}:
 
 {
   name = "lvm";
@@ -10,8 +10,7 @@ start on udev
 script
 
     # Load the device mapper.
-    export MODULE_DIR=${kernel}/lib/modules/
-    ${module_init_tools}/sbin/modprobe dm_mod || true
+    ${modprobe}/sbin/modprobe dm_mod || true
 
     # Scan for block devices that might contain LVM physical volumes
     # and volume groups.
diff --git a/upstart-jobs/network-interfaces.nix b/upstart-jobs/network-interfaces.nix
index 66548b1354d8..a40ced8a90cb 100644
--- a/upstart-jobs/network-interfaces.nix
+++ b/upstart-jobs/network-interfaces.nix
@@ -1,5 +1,4 @@
-# !!! Don't like it that I have to pass the kernel here.
-{ nettools, kernel, module_init_tools, wirelesstools
+{ nettools, modprobe, wirelesstools
 , nameservers, defaultGateway, interfaces
 }:
 
@@ -22,9 +21,7 @@ start on hardware-scan
 stop on shutdown
 
 start script
-    export MODULE_DIR=${kernel}/lib/modules/
-
-    ${module_init_tools}/sbin/modprobe af_packet
+    ${modprobe}/sbin/modprobe af_packet
 
     for i in $(cd /sys/class/net && ls -d *); do
         echo \"Bringing up network device $i...\"
diff --git a/upstart-jobs/ntpd.nix b/upstart-jobs/ntpd.nix
index 39e5eb9023f3..1a043106d17a 100644
--- a/upstart-jobs/ntpd.nix
+++ b/upstart-jobs/ntpd.nix
@@ -1,4 +1,4 @@
-{ntp, kernel, module_init_tools, glibc, pwdutils, writeText, servers}:
+{ntp, modprobe, glibc, pwdutils, writeText, servers}:
 
 let
 
@@ -37,8 +37,7 @@ start script
     chown ${ntpUser} ${stateDir}
 
     # Needed to run ntpd as an unprivileged user.
-    export MODULE_DIR=${kernel}/lib/modules/
-    ${module_init_tools}/sbin/modprobe capability
+    ${modprobe}/sbin/modprobe capability
 
     ${ntp}/bin/ntpd -q -g ${ntpFlags}
     
diff --git a/upstart-jobs/swraid.nix b/upstart-jobs/swraid.nix
index 3a3328eb1f0b..5cf7d82e3833 100644
--- a/upstart-jobs/swraid.nix
+++ b/upstart-jobs/swraid.nix
@@ -1,4 +1,4 @@
-{kernel, module_init_tools, mdadm}:
+{modprobe, mdadm}:
 
 let
 
@@ -16,9 +16,9 @@ start on udev
 script
 
     # Load the necessary RAID personalities.
-    export MODULE_DIR=${kernel}/lib/modules/
+    # !!! hm, doesn't the kernel load these automatically?
     for mod in raid0 raid1 raid5; do
-        ${module_init_tools}/sbin/modprobe $mod || true
+        ${modprobe}/sbin/modprobe $mod || true
     done
 
     # Scan /proc/partitions for RAID devices.