diff --git a/package/base-files/files/lib/upgrade/common.sh b/package/base-files/files/lib/upgrade/common.sh
index ea03f7761f..bed9c188f2 100644
--- a/package/base-files/files/lib/upgrade/common.sh
+++ b/package/base-files/files/lib/upgrade/common.sh
@@ -243,6 +243,7 @@ do_upgrade() {
 	[ -n "$DELAY" ] && sleep "$DELAY"
 	ask_bool 1 "Reboot" && {
 		v "Rebooting system..."
+		umount -a
 		reboot -f
 		sleep 5
 		echo b 2>/dev/null >/proc/sysrq-trigger
diff --git a/package/system/procd/files/nand.sh b/package/system/procd/files/nand.sh
index 8b0564dca2..70b9af559d 100644
--- a/package/system/procd/files/nand.sh
+++ b/package/system/procd/files/nand.sh
@@ -198,6 +198,7 @@ nand_do_upgrade_success() {
 	sync
 	[ -f "$conf_tar" ] && nand_restore_config "$conf_tar"
 	echo "sysupgrade successful"
+	umount -a
 	reboot -f
 }
 
@@ -213,6 +214,7 @@ nand_upgrade_ubinized() {
 
 	if [ ! "$mtdnum" ]; then
 		echo "cannot find mtd device $CI_UBIPART"
+		umount -a
 		reboot -f
 	fi