diff --git a/board/common/overlay/etc/init.d/S00datapart b/board/common/overlay/etc/init.d/S00datapart
index 833548572e..019234c40b 100755
--- a/board/common/overlay/etc/init.d/S00datapart
+++ b/board/common/overlay/etc/init.d/S00datapart
@@ -3,15 +3,17 @@
 test -n "$os_version" || source /etc/init.d/base
 
 msg_begin "Detecting disk device"
-root_part=$(cat /proc/cmdline | grep -oE 'root=[/a-z0-9]+' | cut -d '=' -f 2)
-if [[ "$root_part" =~ ^([/a-z0-9]+)(p[0-9])$ ]]; then  # e.g. /dev/mmcblk0p2
+root_dev=$(cat /proc/cmdline | grep -oE 'root=[/a-z0-9]+' | cut -d '=' -f 2)
+if [[ "$root_dev" =~ ^([/a-z0-9]+)(p[0-9])$ ]]; then  # e.g. /dev/mmcblk0p2
     disk_dev=${BASH_REMATCH[1]}
+    boot_dev=${disk_dev}p1
     data_dev=${disk_dev}p3
-elif [[ "$root_part" =~ ^([/a-z0-9]+)([0-9])$ ]]; then  # e.g. /dev/sdc2
+elif [[ "$root_dev" =~ ^([/a-z0-9]+)([0-9])$ ]]; then  # e.g. /dev/sdc2
     disk_dev=${BASH_REMATCH[1]}
+    boot_dev=${disk_dev}1
     data_dev=${disk_dev}3
 else
-    msg_fail "unknown ($root_part)"
+    msg_fail "unknown ($root_dev)"
     exit 1
 fi
 msg_done "$disk_dev"
@@ -21,10 +23,12 @@ test -b $data_dev && exit 0
 case "$1" in
     start)
         msg_begin "Creating data partition"
+        root_end=$(partx -s -g -o END $root_dev)
+        data_start=$(($root_end + 1))
         echo -e "n
             p
             3
-            \n
+            ${data_start}
             \n
             w" | /sbin/fdisk $disk_dev 2>&1 >/dev/null | grep -v "Device or resource busy" | grep -v '^$'
         partx -a $disk_dev &>/dev/null