diff --git a/contracts/chip1155/BEChipFactory.sol b/contracts/chip1155/BEChipFactory.sol
index 432d86d..dd59f74 100644
--- a/contracts/chip1155/BEChipFactory.sol
+++ b/contracts/chip1155/BEChipFactory.sol
@@ -22,9 +22,14 @@ interface IMintableERC1155 is IERC1155 {
     ) external;
 }
 
+interface IBurnableERC721 is IERC721 {
+    function burn(address owner, uint256 tokenId) external;
+}
+
 
 contract BEChipFactory is Ownable, Initializable, HasSignature {
     IMintableERC1155 public chip;
+    IBurnableERC721 public chipOld;
 
     address public executor;
 
@@ -59,7 +64,8 @@ contract BEChipFactory is Ownable, Initializable, HasSignature {
         address to,
         uint256[] memory ids
     ) external onlyOwner {
-        require(to != address(0), "to address can not be zero");
+        require(to != address(0), "BEChipFactory: to address can not be zero");
+        require(ids.length > 0, "BEChipFactory: ids cannot be empty");
         uint256[] memory amounts = new uint256[](ids.length);
         uint256 len = ids.length;
         for (uint256 i = 0; i < len; ++i) {
@@ -74,6 +80,11 @@ contract BEChipFactory is Ownable, Initializable, HasSignature {
         uint256 saltNonce,
         bytes calldata signature
     ) external{
+        require(ids.length > 0, "BEChipFactory: ids cannot be empty");
+        require(
+            !usedSignatures[signature],
+            "BEChipFactory: signature used. please send another transaction with new signature"
+        );
         address to = _msgSender();
         bytes32 criteriaMessageHash = getMessageHash(
             to,