diff --git a/tests/installer.nix b/tests/installer.nix
index 35f734cd71de..eea72756ea01 100644
--- a/tests/installer.nix
+++ b/tests/installer.nix
@@ -283,19 +283,17 @@ in {
     { createPartitions =
         ''
           $machine->mustSucceed(
-              "parted /dev/vda mklabel msdos",
-              "parted /dev/vda -- mkpart primary ext2 1M 30MB", # /boot
-              "udevadm settle",
-              "parted /dev/vda -- mkpart extended 30M -1s", # extended partition
-              "udevadm settle",
-              "parted /dev/vda -- mkpart logical 30M 1000M", # md0 (root), first device
-              "udevadm settle",
-              "parted /dev/vda -- mkpart logical 1024M 2000M", # md0 (root), second device
-              "udevadm settle",
-              "parted /dev/vda -- mkpart logical 2048M 2548M", # md1 (swap), first device
-              "udevadm settle",
-              "parted /dev/vda -- mkpart logical 2560M 3060M", # md1 (swap), second device
+              "parted /dev/vda --"
+              . " mklabel msdos"
+              . " mkpart primary ext2 1M 30MB" # /boot
+              . " mkpart extended 30M -1s"
+              . " mkpart logical 31M 1000M" # md0 (root), first device
+              . " mkpart logical 1024M 2000M" # md0 (root), second device
+              . " mkpart logical 2048M 2548M" # md1 (swap), first device
+              . " mkpart logical 2560M 3060M", # md1 (swap), second device
               "udevadm settle",
+              "ls -l /dev/vda* >&2",
+              "cat /proc/partitions >&2",
               "mdadm --create --force /dev/md0 --metadata 1.2 --level=raid1 --raid-devices=2 /dev/vda5 /dev/vda6",
               "mdadm --create --force /dev/md1 --metadata 1.2 --level=raid1 --raid-devices=2 /dev/vda7 /dev/vda8",
               "mkswap -f /dev/md1 -L swap",