diff --git a/disk.sh b/disk.sh
index 23bd0cc..226f68d 100644
--- a/disk.sh
+++ b/disk.sh
@@ -1,55 +1,52 @@
 #!/usr/bin/env bash
 set -eu
 
-IMG="/storage"
-BASE=$(basename "$URL" .pat)
+BOOT="$IMG/$BASE.boot.img"
+[ ! -f "$BOOT" ] && echo "ERROR: Virtual DSM boot-image does not exist ($BOOT)" && exit 81
 
-FILE="$IMG/$BASE.boot.img"
-[ ! -f "$FILE" ] && echo "ERROR: Virtual DSM boot-image does not exist ($FILE)" && exit 81
-
-FILE="$IMG/$BASE.system.img"
-[ ! -f "$FILE" ] && echo "ERROR: Virtual DSM system-image does not exist ($FILE)" && exit 82
+SYSTEM="$IMG/$BASE.system.img"
+[ ! -f "$SYSTEM" ] && echo "ERROR: Virtual DSM system-image does not exist ($SYSTEM)" && exit 82
 
 DISK_SIZE=$(echo "${DISK_SIZE}" | sed 's/MB/M/g;s/GB/G/g;s/TB/T/g')
 NEW_SIZE=$(numfmt --from=iec "${DISK_SIZE}")
 
-FILE="$IMG/data$DISK_SIZE.img"
+DATA="$IMG/data$DISK_SIZE.img"
 
-if [ ! -f "$FILE" ]; then
+if [ ! -f "$DATA" ]; then
     # Create an empty file
-    truncate -s "${NEW_SIZE}" "${FILE}"
+    truncate -s "${NEW_SIZE}" "${DATA}"
     # Format as BTRFS filesystem
-    mkfs.btrfs -q -L data -d single -m dup "${FILE}" > /dev/null
+    mkfs.btrfs -q -L data -d single -m dup "${DATA}" > /dev/null
 fi
 
-[ ! -f "$FILE" ] && echo "ERROR: Virtual DSM data-image does not exist ($FILE)" && exit 83
+[ ! -f "$DATA" ] && echo "ERROR: Virtual DSM data-image does not exist ($DATA)" && exit 83
 
 # Resizing requires mounting a loop device which in turn requires
 # the container to be privileged, so we must disable it for now.
 #
-# OLD_SIZE=$(stat -c%s "${FILE}")
+# OLD_SIZE=$(stat -c%s "${DATA}")
 #
 # if [ "$NEW_SIZE" -ne "$OLD_SIZE" ]; then
 #   echo "Resizing data disk from $OLD_SIZE to $NEW_SIZE bytes"
 #
 #   if [ "$NEW_SIZE" -gt "$OLD_SIZE" ]; then
-#     truncate -s "${NEW_SIZE}" "${FILE}"
-#     btrfs filesystem resize "${NEW_SIZE}" "${FILE}"
+#     truncate -s "${NEW_SIZE}" "${DATA}"
+#     btrfs filesystem resize "${NEW_SIZE}" "${DATA}"
 #   fi
 #
 #   if [ "$NEW_SIZE" -lt "$OLD_SIZE" ]; then
-#     btrfs filesystem resize "${NEW_SIZE}" "${FILE}"
-#     truncate -s "${NEW_SIZE}" "${FILE}"
+#     btrfs filesystem resize "${NEW_SIZE}" "${DATA}"
+#     truncate -s "${NEW_SIZE}" "${DATA}"
 #   fi
 # fi
 
 KVM_DISK_OPTS="\
     -device virtio-scsi-pci,id=hw-synoboot,bus=pcie.0,addr=0xa \
-    -drive file=${IMG}/${BASE}.boot.img,if=none,id=drive-synoboot,format=raw,cache=none,aio=native,discard=on,detect-zeroes=on \
+    -drive file=${BOOT},if=none,id=drive-synoboot,format=raw,cache=none,aio=native,discard=on,detect-zeroes=on \
     -device scsi-hd,bus=hw-synoboot.0,channel=0,scsi-id=0,lun=0,drive=drive-synoboot,id=synoboot0,rotation_rate=1,bootindex=1 \
     -device virtio-scsi-pci,id=hw-synosys,bus=pcie.0,addr=0xb \
-    -drive file=${IMG}/${BASE}.system.img,if=none,id=drive-synosys,format=raw,cache=none,aio=native,discard=on,detect-zeroes=on \
+    -drive file=${SYSTEM},if=none,id=drive-synosys,format=raw,cache=none,aio=native,discard=on,detect-zeroes=on \
     -device scsi-hd,bus=hw-synosys.0,channel=0,scsi-id=0,lun=0,drive=drive-synosys,id=synosys0,rotation_rate=1,bootindex=2 \
     -device virtio-scsi-pci,id=hw-userdata,bus=pcie.0,addr=0xc \
-    -drive file=${IMG}/data${DISK_SIZE}.img,if=none,id=drive-userdata,format=raw,cache=none,aio=native,discard=on,detect-zeroes=on \
+    -drive file=${DATA},if=none,id=drive-userdata,format=raw,cache=none,aio=native,discard=on,detect-zeroes=on \
     -device scsi-hd,bus=hw-userdata.0,channel=0,scsi-id=0,lun=0,drive=drive-userdata,id=userdata0,rotation_rate=1,bootindex=3"