diff --git a/src/BTCDepositAddressDeriver.sol b/src/BTCDepositAddressDeriver.sol
index 00ac591..aeb04d2 100644
--- a/src/BTCDepositAddressDeriver.sol
+++ b/src/BTCDepositAddressDeriver.sol
@@ -17,7 +17,7 @@ error CannotParseBtcAddress(
 
 // Types of Bitcoin Network
 
-contract BTCDepositAddressDeriver {
+contract BTCDepositAddressDeriver is Bech32m, Deriver {
 
     event SeedChanged(string btcAddr1, string btcAddr2, string hrp);
 
diff --git a/src/Bech32m.sol b/src/Bech32m.sol
index 7340d51..32001b7 100644
--- a/src/Bech32m.sol
+++ b/src/Bech32m.sol
@@ -7,7 +7,7 @@ pragma solidity ^0.8.24;
 
 error EncodingIsUnknown();
 
-library Bech32m {
+contract Bech32m {
 
     enum BechEncoding {
         // Used is SegWit v.0
@@ -50,49 +50,6 @@ library Bech32m {
         IncorrectEncodingForSegwitVn
     }
 
-    function explainDecodeError(DecodeError err) public pure returns (string memory) {
-        if (err == DecodeError.NoError) {
-            return string("No error");
-        } else if (err == DecodeError.IncorrectPadding) {
-            return string("Incorrect Padding");
-        } else if (err == DecodeError.IncorrectLength) {
-            return string("Incorrect address length");
-        } else if (err == DecodeError.CharacterOutOfRange) {
-            return string("Address contain character out of range");
-        } else if (err == DecodeError.MixedCase) {
-            return string("Address consists of both capital and small letters");
-        } else if (err == DecodeError.IncorrectChecksum) {
-            return string("Address checksum does not match");
-        } else if (err == DecodeError.TooShortChecksum) {
-            return string("Address checksum is too short");
-        } else if (err == DecodeError.InputIsTooLong) {
-            return string("Address is too long");
-        } else if (err == DecodeError.NotBech32Character) {
-            return string("Address contains character which is not in bech32 encoding");
-        } else if (err == DecodeError.HRPIsEmpty) {
-            return string("Network prefix is empty");
-        } else if (err == DecodeError.NoDelimiter) {
-            return string("No prefix delimiter in the address");
-        } else if (err == DecodeError.HRPMismatch) {
-            return string("Network prefix is different from expected");
-        } else if (err == DecodeError.WitnessProgramTooSmall) {
-            return string("Witness program should be at least 2 bytes");
-        } else if (err == DecodeError.EmptyData) {
-            return string("Witness program is empty");
-        } else if (err == DecodeError.WitnessProgramTooLarge) {
-            return string("Witness program should be maximum 40 bytes");
-        } else if (err == DecodeError.SegwitVersionTooLarge) {
-            return string("Segwit version should be from 0 to 16 (including). Got some larger number.");
-        } else if (err == DecodeError.IncorrectSegwitV0Program) {
-            return string("Length of segwit v0 program should be either 20 or 32 bytes");
-        } else if (err == DecodeError.IncorrectEncodingForSegwitV0) {
-            return string("Segwit v0 should be encoded using Bech32");
-        } else if (err == DecodeError.IncorrectEncodingForSegwitVn) {
-            return string("Segwit with versions 1-16 should be encoded with Bech32m");
-        }
-        return "";
-}
-
     // Possible characters for Bitcoin address
     bytes internal constant CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l";
 
@@ -617,7 +574,7 @@ library Bech32m {
 
     // Decode a segwit address
     function decodeSegwitAddress(
-        bytes calldata expectedHrp,
+        bytes memory expectedHrp,
         bytes calldata addr
     ) public pure returns (uint8, bytes memory, DecodeError) {
         (
diff --git a/src/Deriver.sol b/src/Deriver.sol
index dea32bb..befeafb 100644
--- a/src/Deriver.sol
+++ b/src/Deriver.sol
@@ -6,7 +6,7 @@ import {EllipticCurve} from "../lib/elliptic-curve-solidity/contracts/EllipticCu
 
 import {Bech32m} from "./Bech32m.sol";
 
-library Deriver {
+contract Deriver is Bech32m {
 
     // BEGIN SECP256k1 CONSTANTS
     uint256 public constant GX =