diff --git a/prebuilt/common/bin/backuptool.sh b/prebuilt/common/bin/backuptool.sh
index 9c620461..e873b2ed 100755
--- a/prebuilt/common/bin/backuptool.sh
+++ b/prebuilt/common/bin/backuptool.sh
@@ -126,12 +126,12 @@ case "$1" in
     mount_system
     mkdir -p $C
     if check_prereq; then
-        if check_whitelist system; then
+        if check_whitelist $S; then
             unmount_system
             exit 127
         fi
     fi
-    check_blacklist system
+    check_blacklist $S
     preserve_addon_d
     run_stage pre-backup
     run_stage backup