diff --git a/README.md b/README.md
index c6b92b9..bf10c36 100644
--- a/README.md
+++ b/README.md
@@ -48,7 +48,7 @@ Get Kaspa address (public key) for a BIP32 path.
 ##### Examples
 
 ```javascript
-kaspa.getAddress("44'/501'/0'").then(r => r.address)
+kaspa.getAddress("44'/111111'/0'").then(r => r.address)
 ```
 
 Returns **[Promise](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise)<{address: [Buffer](https://nodejs.org/api/buffer.html)}>** an object with the address field
@@ -80,19 +80,26 @@ const txin = new TransactionInput({
 });
 
 const txout = new TransactionOutput({
-    value: 1090000,
+    value: 1000000,
+    scriptPublicKey: "2011a7215f668e921013eb7aac9b7e64b9ec6e757c1b648e89388c919f676aa88cac",
+});
+
+// By convention, the second output MUST be the change address
+// It MUST set both addressType and addressIndex
+const txoutchange = new TransactionOutput({
+    value: 90000,
     scriptPublicKey: "2011a7215f668e921013eb7aac9b7e64b9ec6e757c1b648e89388c919f676aa88cac",
 });
 
 const tx = new Transaction({
     version: 0,
+    changeAddressType: 0,
+    changeAddressIndex: 0,
     inputs: [txin],
-    outputs: [txout],
+    outputs: [txout, txoutchange],
 });
 
 kaspa.signTransaction(tx);
 ```
 
-Updates the 
-
-
+Updates the transaction by filling in the `signature` property of each `TransactionInput` in the `Transaction` object.
diff --git a/src/kaspa.js b/src/kaspa.js
index 82b0bb5..7878c2e 100644
--- a/src/kaspa.js
+++ b/src/kaspa.js
@@ -94,9 +94,6 @@ class Kaspa {
         if (!(transaction instanceof Transaction)) {
             throw new Error("transaction must be an instance of Transaction");
         }
-        // Ledger app supports only a single derivation path per call ATM
-        const pathsCountBuffer = Buffer.alloc(1);
-        pathsCountBuffer.writeUInt8(1, 0);
 
         const header = transaction.serialize();
 
diff --git a/src/transaction.js b/src/transaction.js
index f648800..b136127 100644
--- a/src/transaction.js
+++ b/src/transaction.js
@@ -14,6 +14,17 @@ class Transaction {
          * @type {int}
          */
         this.version = txData.version;
+
+        this.changeAddressType = Number.isInteger(txData.changeAddressType) ? txData.changeAddressType : 0;
+        this.changeAddressIndex = Number.isInteger(txData.changeAddressIndex) ? txData.changeAddressIndex : 0;
+
+        if (!(this.changeAddressType === 0 || this.changeAddressType === 1)) {
+            throw new Error(`changeAddressType must be 0 or 1 if set`);
+        }
+
+        if (this.changeAddressIndex < 0x00000000 || this.changeAddressIndex > 0xFFFFFFFF) {
+            throw new Error(`changeAddressIndex must be between 0x00000000 and 0xFFFFFFFF`);
+        }
     }
 
     serialize() {
@@ -26,10 +37,18 @@ class Transaction {
         const inputLenBuf = Buffer.alloc(1);
         inputLenBuf.writeUInt8(this.inputs.length);
 
+        const changeAddressTypeBuf = Buffer.alloc(1);
+        changeAddressTypeBuf.writeUInt8(this.changeAddressType || 0);
+
+        const changeAddressIndexBuf = Buffer.alloc(4);
+        changeAddressIndexBuf.writeUInt32BE(this.changeAddressIndex || 0);
+
         return Buffer.concat([
             versionBuf,
             outputLenBuf,
             inputLenBuf,
+            changeAddressTypeBuf,
+            changeAddressIndexBuf,
         ]);
     }
 
@@ -116,7 +135,15 @@ class TransactionInput {
 
 class TransactionOutput {
     constructor(outputData = {}) {
+        if (!outputData.value || outputData.value < 0 || outputData.value > 0xFFFFFFFFFFFFFFFF) {
+            throw new Error('value must be set to a value greater than 0 and less than 0xFFFFFFFFFFFFFFFF');
+        }
         this.value = outputData.value;
+        if (!outputData.scriptPublicKey) {
+            throw new Error('scriptPublicKey must be set');
+        }
+
+        // Only then do we care about the script public key
         this.scriptPublicKey = outputData.scriptPublicKey;
     }
 
diff --git a/tests/kaspa.test.js b/tests/kaspa.test.js
index 41e48b2..bf1aded 100644
--- a/tests/kaspa.test.js
+++ b/tests/kaspa.test.js
@@ -47,7 +47,7 @@ describe("kaspa", () => {
     it("signTransaction with simple data", async () => {
         const transport = await openTransportReplayer(
             RecordStore.fromString(`
-                => e00600800400000101
+                => e006008009000001010102030405
                 <= 9000
                 => e00601802a000000000010a1d02011a7215f668e921013eb7aac9b7e64b9ec6e757c1b648e89388c919f676aa88cac
                 <= 9000
@@ -74,6 +74,8 @@ describe("kaspa", () => {
             version: 0,
             inputs: [txin],
             outputs: [txout],
+            changeAddressType: 1,
+            changeAddressIndex: 0x02030405,
         });
 
         await kaspa.signTransaction(tx);
@@ -81,3 +83,117 @@ describe("kaspa", () => {
         expect(txin.sighash).toEqual("00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff");
     });
 });
+
+describe("Transaction", () => {
+    it("should serialize", () => {
+        const txin = new TransactionInput({
+            prevTxId: "40b022362f1a303518e2b49f86f87a317c87b514ca0f3d08ad2e7cf49d08cc70",
+            value: 1100000,
+            addressType: 0,
+            addressIndex: 0,
+            outpointIndex: 0,
+        });
+
+        const txout = new TransactionOutput({
+            value: 1090000,
+            scriptPublicKey: "2011a7215f668e921013eb7aac9b7e64b9ec6e757c1b648e89388c919f676aa88cac",
+        });
+
+        const tx = new Transaction({
+            version: 0,
+            inputs: [txin],
+            outputs: [txout],
+            changeAddressType: 1,
+            changeAddressIndex: 0x02030405
+        });
+
+        const expectation = Buffer.from([0x00, 0x00, 0x01, 0x01, 0x01, 0x02, 0x03, 0x04, 0x05]);
+
+        expect(tx.serialize().equals(expectation)).toBeTruthy();
+    });
+});
+
+describe("TransactionOutput", () => {
+    it("should throw no error if only scriptPublicKey and value is set", () => {
+        let err = null;
+        try {
+            new TransactionOutput({
+                value: 1090000,
+                scriptPublicKey: "2011a7215f668e921013eb7aac9b7e64b9ec6e757c1b648e89388c919f676aa88cac",
+            });
+        } catch (e) {
+            err = e;
+        }
+
+        expect(err).toBe(null);
+    });
+
+    it("should serialize value and scriptPublicKey", () => {
+        const serial = new TransactionOutput({
+            value: 1090000,
+            scriptPublicKey: "2011a7215f668e921013eb7aac9b7e64b9ec6e757c1b648e89388c919f676aa88cac",
+        }).serialize();
+
+        const expectation = Buffer.from([
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0xa1, 0xd0,
+            0x20, 0x11, 0xa7, 0x21, 0x5f, 0x66, 0x8e, 0x92,
+            0x10, 0x13, 0xeb, 0x7a, 0xac, 0x9b, 0x7e, 0x64,
+            0xb9, 0xec, 0x6e, 0x75, 0x7c, 0x1b, 0x64, 0x8e,
+            0x89, 0x38, 0x8c, 0x91, 0x9f, 0x67, 0x6a, 0xa8,
+            0x8c, 0xac,
+        ]);
+        
+        expect(serial.equals(expectation)).toBeTruthy();
+    });
+
+    it("should throw errors if none of scriptPublicKey or (addressType, addressIndex) are set", () => {
+        let err = null;
+        try {
+            new TransactionOutput({
+                value: 1090000
+            });
+        } catch (e) {
+            err = e;
+        }
+
+        expect(err).not.toBe(null);
+    });
+
+    it("should throw errors if value is not set", () => {
+        let err = null;
+        try {
+            new TransactionOutput({
+                scriptPublicKey: "2011a7215f668e921013eb7aac9b7e64b9ec6e757c1b648e89388c919f676aa88cac",
+            });
+        } catch (e) {
+            err = e;
+        }
+
+        expect(err).not.toBe(null);
+    });
+
+    it("should throw errors if value is < 0 or > 0xFFFFFFFFFFFFFFFF", () => {
+        let err = null;
+        try {
+            new TransactionOutput({
+                value: 0,
+                scriptPublicKey: "2011a7215f668e921013eb7aac9b7e64b9ec6e757c1b648e89388c919f676aa88cac",
+            });
+        } catch (e) {
+            err = e;
+        }
+
+        expect(err).not.toBe(null);
+
+        try {
+            new TransactionOutput({
+                value: 0xFFFFFFFFFFFFFFFF + 1,
+                scriptPublicKey: "2011a7215f668e921013eb7aac9b7e64b9ec6e757c1b648e89388c919f676aa88cac",
+            });
+        } catch (e) {
+            err = e;
+        }
+
+        expect(err).not.toBe(null);
+    });
+});