diff --git a/README.md b/README.md
index e9b5823..98eab83 100644
--- a/README.md
+++ b/README.md
@@ -43,6 +43,7 @@ This tool can parse and dump WeChat chat history on a rooted android phone.
 + Add nickname in chatroom
 + Show name of emoji in text output
 + Search by uid/username
++ Skip existing files when copying android resources
 + Better user experiences... see TODOs
 
 ### Disclaimers
diff --git a/decrypt_db.sh b/decrypt_db.sh
index 5ef9664..0f53705 100755
--- a/decrypt_db.sh
+++ b/decrypt_db.sh
@@ -1,6 +1,6 @@
 #!/bin/bash -e
 # File: decrypt_db.sh
-# Date: Wed Dec 31 23:38:16 2014 +0800
+# Date: Wed Jan 07 22:08:56 2015 +0800
 # Author: Yuxin Wu <ppwwyyxxc@gmail.com>
 
 MSGDB=$1
@@ -13,6 +13,13 @@ if [[ -z "$1" || -z "$2" || -z "$3" ]]; then
 	exit
 fi
 
+if [[ -f $output ]]; then
+	echo "$output already exists. removed? (y/n)"
+	read r
+	[[ $r == "y" ]] && rm -v $output || exit 1
+fi
+
+
 KEY=$(echo -n "$imei$uin" | md5sum | cut -b 1-7)
 echo "KEY: $KEY"