diff --git a/package/base-files/files/lib/upgrade/common.sh b/package/base-files/files/lib/upgrade/common.sh
index ec198b2375c..24ff77a8b31 100644
--- a/package/base-files/files/lib/upgrade/common.sh
+++ b/package/base-files/files/lib/upgrade/common.sh
@@ -245,7 +245,7 @@ get_partitions() { # <device> <filename>
 				local type="$1"
 				local lba="$(( $(hex_le32_to_cpu $4) * 0x100000000 + $(hex_le32_to_cpu $3) ))"
 				local end="$(( $(hex_le32_to_cpu $6) * 0x100000000 + $(hex_le32_to_cpu $5) ))"
-				local num="$(( $end - $lba ))"
+				local num="$(( $end - $lba + 1 ))"
 
 				[ "$type" = "00000000000000000000000000000000" ] && continue