diff --git a/prebuilt/common/bin/backuptool.sh b/prebuilt/common/bin/backuptool.sh
index cc983556..8e9e7322 100755
--- a/prebuilt/common/bin/backuptool.sh
+++ b/prebuilt/common/bin/backuptool.sh
@@ -137,7 +137,11 @@ find_block() {
 determine_system_mount
 
 DYNAMIC_PARTITIONS=$(getprop ro.boot.dynamic_partitions)
-BLK_PATH=$(dirname "$SYSDEV")
+if [ "$DYNAMIC_PARTITIONS" = "true" ]; then
+    BLK_PATH="/dev/block/mapper"
+else
+    BLK_PATH=$(dirname "$SYSDEV")
+fi
 
 mount_extra() {
   for partition in $@; do