diff --git a/src/install.sh b/src/install.sh
index 5cfd64f..07ddc3b 100644
--- a/src/install.sh
+++ b/src/install.sh
@@ -366,7 +366,7 @@ genisoimage -b "$ETFS" -no-emul-boot -c "$CAT" -iso-level 4 -J -l -D -N -joliet-
                        -boot-info-table -eltorito-alt-boot -eltorito-boot "$EFISYS" -no-emul-boot -o "$OUT" -allow-limited-size "$DIR"
 
 # Mark ISO as prepared via magic byte
-printf '\x16' | dd of=$ISO bs=1 seek=0 count=1 conv=notrunc status=none
+printf '\x16' | dd of=$OUT bs=1 seek=0 count=1 conv=notrunc status=none
 
 [ -n "$CUSTOM" ] && rm -f "$STORAGE/$CUSTOM"