diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8178428..3d0b05c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## [1.8.3] - 16.Jul.2024.
+- improve request headers handling
+- change sequence number from int to BigInt (web issue)
+
 ## [1.8.2] - 1.Jul.2024.
 - null safety improvements
 - add support for large amounts on web
diff --git a/README.md b/README.md
index b5be00d..4998ca0 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ The Soneso open source Stellar SDK for Flutter is build with Dart and provides A
 1. Add the dependency to your pubspec.yaml file:
 ```
 dependencies:
-  stellar_flutter_sdk: ^1.8.2
+  stellar_flutter_sdk: ^1.8.3
 ```
 2. Install it (command line or IDE):
 ```
diff --git a/documentation/sdk_examples/bump_sequence.md b/documentation/sdk_examples/bump_sequence.md
index 27212c7..e9aba9b 100644
--- a/documentation/sdk_examples/bump_sequence.md
+++ b/documentation/sdk_examples/bump_sequence.md
@@ -21,7 +21,7 @@ int startSequence = account.sequenceNumber;
 
 // Prepare the bump sequence operation to bump the sequence number to current + 10.
 BumpSequenceOperationBuilder bumpSequenceOpB =
-BumpSequenceOperationBuilder(startSequence + 10);
+BumpSequenceOperationBuilder(startSequence + BigInt.from(10));
 
 // Prepare the transaction.
 Transaction transaction = TransactionBuilder(account)
@@ -38,7 +38,7 @@ await sdk.submitTransaction(transaction);
 account = await sdk.accounts.account(accountId);
 
 // Check that the new sequence number has correctly been bumped.
-if(startSequence + 10 == account.sequenceNumber) {
+if(startSequence + BigInt.from(10) == account.sequenceNumber) {
   print("success");
 } else {
   print("failed");
diff --git a/lib/src/account.dart b/lib/src/account.dart
index b711268..befe37b 100644
--- a/lib/src/account.dart
+++ b/lib/src/account.dart
@@ -10,10 +10,10 @@ abstract class TransactionBuilderAccount {
   String get accountId;
 
   /// Returns current sequence number ot this Account.
-  int get sequenceNumber;
+  BigInt get sequenceNumber;
 
   /// Returns sequence number incremented by one, but does not increment internal counter.
-  int get incrementedSequenceNumber;
+  BigInt get incrementedSequenceNumber;
 
   // Muxed account object created from this account object.
   MuxedAccount get muxedAccount;
@@ -26,7 +26,7 @@ abstract class TransactionBuilderAccount {
 /// Account object is required to build a [Transaction].
 class Account implements TransactionBuilderAccount {
   String _accountId;
-  int _mSequenceNumber;
+  BigInt _mSequenceNumber;
   late MuxedAccount _muxedAccount;
 
   Account(this._accountId, this._mSequenceNumber,
@@ -34,7 +34,7 @@ class Account implements TransactionBuilderAccount {
     this._muxedAccount = MuxedAccount(this._accountId, muxedAccountMed25519Id);
   }
 
-  static Account fromAccountId(String accountId, int sequenceNumber) {
+  static Account fromAccountId(String accountId, BigInt sequenceNumber) {
     MuxedAccount mux = MuxedAccount.fromAccountId(accountId)!;
     return new Account(mux.ed25519AccountId, sequenceNumber,
         muxedAccountMed25519Id: mux.id);
@@ -44,16 +44,16 @@ class Account implements TransactionBuilderAccount {
   String get accountId => _accountId;
 
   @override
-  int get sequenceNumber => _mSequenceNumber;
+  BigInt get sequenceNumber => _mSequenceNumber;
 
   @override
   MuxedAccount get muxedAccount => _muxedAccount;
 
   @override
-  int get incrementedSequenceNumber => _mSequenceNumber + 1;
+  BigInt get incrementedSequenceNumber => _mSequenceNumber + BigInt.one;
 
   /// Increments sequence number in this account object by one.
   void incrementSequenceNumber() {
-    _mSequenceNumber = _mSequenceNumber + 1;
+    _mSequenceNumber = _mSequenceNumber +  BigInt.one;
   }
 }
diff --git a/lib/src/bump_sequence_operation.dart b/lib/src/bump_sequence_operation.dart
index 5235596..2bf70a1 100644
--- a/lib/src/bump_sequence_operation.dart
+++ b/lib/src/bump_sequence_operation.dart
@@ -13,15 +13,15 @@ import 'xdr/xdr_type.dart';
 /// Represents <a href="https://developers.stellar.org/docs/start/list-of-operations/#bump-sequence" target="_blank">Bump Sequence</a> operation.
 /// See: <a href="https://developers.stellar.org/docs/start/list-of-operations/" target="_blank">List of Operations</a>
 class BumpSequenceOperation extends Operation {
-  int _bumpTo;
+  BigInt _bumpTo;
 
   BumpSequenceOperation(this._bumpTo);
 
-  int get bumpTo => _bumpTo;
+  BigInt get bumpTo => _bumpTo;
 
   @override
   XdrOperationBody toOperationBody() {
-    XdrInt64 bumpTo = new XdrInt64(this._bumpTo);
+    XdrBigInt64 bumpTo = new XdrBigInt64(this._bumpTo);
     XdrOperationBody body =
         new XdrOperationBody(XdrOperationType.BUMP_SEQUENCE);
     body.bumpSequenceOp = new XdrBumpSequenceOp(XdrSequenceNumber(bumpTo));
@@ -31,12 +31,12 @@ class BumpSequenceOperation extends Operation {
 
   /// Construct a new BumpSequence builder from a BumpSequence XDR.
   static BumpSequenceOperationBuilder builder(XdrBumpSequenceOp op) {
-    return BumpSequenceOperationBuilder(op.bumpTo.sequenceNumber.int64);
+    return BumpSequenceOperationBuilder(op.bumpTo.sequenceNumber.bigInt);
   }
 }
 
 class BumpSequenceOperationBuilder {
-  int _bumpTo;
+  BigInt _bumpTo;
   MuxedAccount? _mSourceAccount;
 
   /// Creates a new BumpSequence builder.
diff --git a/lib/src/responses/account_response.dart b/lib/src/responses/account_response.dart
index 23e9798..5231d7c 100644
--- a/lib/src/responses/account_response.dart
+++ b/lib/src/responses/account_response.dart
@@ -15,7 +15,7 @@ import 'response.dart';
 /// See: <a href="https://developers.stellar.org/api/resources/accounts/" target="_blank">Account documentation</a>.
 class AccountResponse extends Response implements TransactionBuilderAccount {
   String accountId;
-  int _sequenceNumber;
+  BigInt _sequenceNumber;
   String pagingToken;
   int subentryCount;
   String? inflationDestination;
@@ -61,13 +61,13 @@ class AccountResponse extends Response implements TransactionBuilderAccount {
   KeyPair get keypair => KeyPair.fromAccountId(accountId);
 
   @override
-  int get sequenceNumber => _sequenceNumber;
+  BigInt get sequenceNumber => _sequenceNumber;
 
   @override
-  int get incrementedSequenceNumber => _sequenceNumber + 1;
+  BigInt get incrementedSequenceNumber => _sequenceNumber + BigInt.one;
 
   @override
-  void incrementSequenceNumber() => _sequenceNumber = _sequenceNumber + 1;
+  void incrementSequenceNumber() => _sequenceNumber = _sequenceNumber + BigInt.one;
 
   @override
   MuxedAccount get muxedAccount =>
@@ -76,7 +76,7 @@ class AccountResponse extends Response implements TransactionBuilderAccount {
   factory AccountResponse.fromJson(Map<String, dynamic> json) =>
       AccountResponse(
         json['account_id'],
-        convertInt(json['sequence'])!,
+        BigInt.parse(json['sequence']),
         json['paging_token'],
         convertInt(json['subentry_count'])!,
         json['inflation_destination'],
diff --git a/lib/src/sep/0010/webauth.dart b/lib/src/sep/0010/webauth.dart
index ab92179..d465007 100644
--- a/lib/src/sep/0010/webauth.dart
+++ b/lib/src/sep/0010/webauth.dart
@@ -152,7 +152,7 @@ class WebAuth {
 
     final transaction = envelopeXdr.v1!.tx;
 
-    if (transaction.seqNum.sequenceNumber.int64 != 0) {
+    if (transaction.seqNum.sequenceNumber.bigInt != BigInt.zero) {
       throw ChallengeValidationErrorInvalidSeqNr(
           "Invalid transaction, sequence number not 0");
     }
diff --git a/lib/src/sep/0011/txrep.dart b/lib/src/sep/0011/txrep.dart
index 54a42ca..a42e81c 100644
--- a/lib/src/sep/0011/txrep.dart
+++ b/lib/src/sep/0011/txrep.dart
@@ -134,15 +134,11 @@ class TxRep {
     }
 
     String? seqNr = _removeComment(map['${prefix}seqNum']);
-    int? sequenceNumber;
+    BigInt? sequenceNumber;
     if (seqNr == null) {
       throw Exception('missing ${prefix}seqNum');
     } else {
-      try {
-        sequenceNumber = int.tryParse(seqNr);
-      } catch (e) {
-        throw Exception('invalid ${prefix}seqNum');
-      }
+      sequenceNumber = BigInt.tryParse(seqNr);
     }
     if (sequenceNumber == null) {
       throw Exception('invalid ${prefix}seqNum');
@@ -155,7 +151,7 @@ class TxRep {
     }
 
     MuxedAccount? mux = MuxedAccount.fromAccountId(sourceAccountId);
-    Account sourceAccount = Account(mux!.ed25519AccountId, sequenceNumber - 1,
+    Account sourceAccount = Account(mux!.ed25519AccountId, sequenceNumber - BigInt.one,
         muxedAccountMed25519Id: mux.id);
     TransactionBuilder txBuilder = TransactionBuilder(sourceAccount);
     txBuilder.addPreconditions(_getPreconditions(map, prefix));
@@ -300,8 +296,8 @@ class TxRep {
 
       if (_removeComment(map['${precondPrefix}minSeqNum._present']) == 'true' &&
           map['${precondPrefix}minSeqNum'] != null) {
-        int? minSeqNum =
-            int.tryParse(_removeComment(map['${precondPrefix}minSeqNum'])!);
+        BigInt? minSeqNum =
+        BigInt.tryParse(_removeComment(map['${precondPrefix}minSeqNum'])!);
         if (minSeqNum == null) {
           throw Exception('invalid ${precondPrefix}minSeqNum');
         }
@@ -2701,12 +2697,8 @@ class TxRep {
       throw Exception('missing $opPrefix' + 'bumpTo');
     }
 
-    int? bumpTo;
-    try {
-      bumpTo = int.tryParse(bumpToStr);
-    } catch (e) {
-      throw Exception('invalid $opPrefix' + 'bumpTo');
-    }
+    BigInt? bumpTo = BigInt.tryParse(bumpToStr);
+
     if (bumpTo == null) {
       throw Exception('invalid $opPrefix' + 'bumpTo');
     }
diff --git a/lib/src/soroban/soroban_server.dart b/lib/src/soroban/soroban_server.dart
index 2f681ce..d14b093 100644
--- a/lib/src/soroban/soroban_server.dart
+++ b/lib/src/soroban/soroban_server.dart
@@ -121,7 +121,7 @@ class SorobanServer {
         String accountId =
             KeyPair.fromXdrPublicKey(accountEntry.accountID.accountID)
                 .accountId;
-        int seqNr = accountEntry.seqNum.sequenceNumber.int64;
+        BigInt seqNr = accountEntry.seqNum.sequenceNumber.bigInt;
         return Account(accountId, seqNr);
       }
     }
diff --git a/lib/src/stellar_sdk.dart b/lib/src/stellar_sdk.dart
index 81db11d..5035a4f 100644
--- a/lib/src/stellar_sdk.dart
+++ b/lib/src/stellar_sdk.dart
@@ -31,7 +31,7 @@ import 'requests/liquidity_pools_request_builder.dart';
 
 /// Main class of the flutter stellar sdk.
 class StellarSDK {
-  static const versionNumber = "1.8.2";
+  static const versionNumber = "1.8.3";
 
   static final StellarSDK PUBLIC = StellarSDK("https://horizon.stellar.org");
   static final StellarSDK TESTNET = StellarSDK("https://horizon-testnet.stellar.org");
diff --git a/lib/src/transaction.dart b/lib/src/transaction.dart
index baceb96..d3ee5ba 100644
--- a/lib/src/transaction.dart
+++ b/lib/src/transaction.dart
@@ -104,7 +104,7 @@ class Transaction extends AbstractTransaction {
   set fee(int value) => this._mFee = value;
 
   MuxedAccount _mSourceAccount;
-  int _mSequenceNumber;
+  BigInt _mSequenceNumber;
   List<Operation> _mOperations;
   Memo? _mMemo;
   TransactionPreconditions? _mPreconditions;
@@ -144,7 +144,7 @@ class Transaction extends AbstractTransaction {
 
   MuxedAccount get sourceAccount => _mSourceAccount;
 
-  int get sequenceNumber => _mSequenceNumber;
+  BigInt get sequenceNumber => _mSequenceNumber;
 
   Memo? get memo => _mMemo;
 
@@ -163,7 +163,7 @@ class Transaction extends AbstractTransaction {
     // fee
     XdrUint32 fee = XdrUint32(_mFee);
     // sequenceNumber
-    XdrInt64 sequenceNumberUint = XdrInt64(_mSequenceNumber);
+    XdrBigInt64 sequenceNumberUint = XdrBigInt64(_mSequenceNumber);
 
     XdrPublicKey sourcePublickKey =
         KeyPair.fromAccountId(_mSourceAccount.ed25519AccountId).xdrPublicKey;
@@ -202,7 +202,7 @@ class Transaction extends AbstractTransaction {
     XdrUint32 fee = XdrUint32(_mFee);
 
     // sequenceNumber
-    XdrInt64 sequenceNumberUint = XdrInt64(_mSequenceNumber);
+    XdrBigInt64 sequenceNumberUint = XdrBigInt64(_mSequenceNumber);
 
     // operations
     List<XdrOperation> operations = List<XdrOperation>.empty(
@@ -238,7 +238,7 @@ class Transaction extends AbstractTransaction {
     XdrTransaction? tx = envelope.tx;
     int mFee = tx.fee.uint32;
 
-    int mSequenceNumber = tx.seqNum.sequenceNumber.int64;
+    BigInt mSequenceNumber = tx.seqNum.sequenceNumber.bigInt;
     Memo? mMemo = Memo.fromXdr(tx.memo);
     TransactionPreconditions mPreconditions =
         TransactionPreconditions.fromXdr(tx.preconditions);
@@ -272,7 +272,7 @@ class Transaction extends AbstractTransaction {
     int? mFee = tx.fee.uint32;
     String mSourceAccount =
         KeyPair.fromPublicKey(tx.sourceAccountEd25519.uint256).accountId;
-    int mSequenceNumber = tx.seqNum.sequenceNumber.int64;
+    BigInt mSequenceNumber = tx.seqNum.sequenceNumber.bigInt;
     Memo mMemo = Memo.fromXdr(tx.memo);
     TimeBounds? mTimeBounds = TimeBounds.fromXdr(tx.timeBounds!);
 
@@ -683,21 +683,21 @@ class TransactionPreconditions {
 
   TimeBounds? _timeBounds;
   LedgerBounds? _ledgerBounds;
-  int? _minSeqNumber;
+  BigInt? _minSeqNumber;
   int? _minSeqAge;
   int? _minSeqLedgerGap;
   List<XdrSignerKey>? _extraSigners;
 
   TimeBounds? get timeBounds => _timeBounds;
   LedgerBounds? get ledgerBounds => _ledgerBounds;
-  int? get minSeqNumber => _minSeqNumber;
+  BigInt? get minSeqNumber => _minSeqNumber;
   int? get minSeqAge => _minSeqAge;
   int? get minSeqLedgerGap => _minSeqLedgerGap;
   List<XdrSignerKey>? get extraSigners => _extraSigners;
 
   set timeBounds(TimeBounds? value) => _timeBounds = value;
   set ledgerBounds(LedgerBounds? value) => _ledgerBounds = value;
-  set minSeqNumber(int? value) => _minSeqNumber = value;
+  set minSeqNumber(BigInt? value) => _minSeqNumber = value;
   set minSeqAge(int? value) => _minSeqAge = value;
   set minSeqLedgerGap(int? value) => _minSeqLedgerGap = value;
   set extraSigners(List<XdrSignerKey>? value) => _extraSigners = value;
@@ -712,7 +712,7 @@ class TransactionPreconditions {
         result.ledgerBounds = LedgerBounds.fromXdr(xdr.v2!.ledgerBounds!);
       }
       if (xdr.v2!.sequenceNumber != null) {
-        result.minSeqNumber = xdr.v2!.sequenceNumber!.uint64;
+        result.minSeqNumber = xdr.v2!.sequenceNumber!.bigInt;
       }
       result.minSeqAge = xdr.v2!.minSeqAge.uint64;
       result.minSeqLedgerGap = xdr.v2!.minSeqLedgerGap.uint32;
@@ -733,7 +733,7 @@ class TransactionPreconditions {
     return _ledgerBounds != null ||
         (_minSeqLedgerGap != null && _minSeqLedgerGap! > 0) ||
         (_minSeqAge != null && _minSeqAge! > 0) ||
-        (_minSeqNumber != null && _minSeqNumber! > 0) ||
+        (_minSeqNumber != null && _minSeqNumber! > BigInt.zero) ||
         (_extraSigners != null && _extraSigners!.length > 0);
   }
 
@@ -766,7 +766,7 @@ class TransactionPreconditions {
       XdrPreconditionsV2 v2 = XdrPreconditionsV2(sa, sl, es);
 
       if (_minSeqNumber != null) {
-        XdrUint64 sn = XdrUint64(_minSeqNumber!);
+        XdrBigInt64 sn = XdrBigInt64(_minSeqNumber!);
         v2.sequenceNumber = sn;
       }
 
diff --git a/lib/src/xdr/xdr_account.dart b/lib/src/xdr/xdr_account.dart
index 049ac86..247416a 100644
--- a/lib/src/xdr/xdr_account.dart
+++ b/lib/src/xdr/xdr_account.dart
@@ -2172,21 +2172,21 @@ class XdrSetOptionsOp {
 }
 
 class XdrSequenceNumber {
-  XdrInt64 _sequenceNumber;
+  XdrBigInt64 _sequenceNumber;
 
-  XdrInt64 get sequenceNumber => this._sequenceNumber;
+  XdrBigInt64 get sequenceNumber => this._sequenceNumber;
 
-  set sequenceNumber(XdrInt64 value) => this._sequenceNumber = value;
+  set sequenceNumber(XdrBigInt64 value) => this._sequenceNumber = value;
 
   XdrSequenceNumber(this._sequenceNumber);
 
   static void encode(
       XdrDataOutputStream stream, XdrSequenceNumber encodedSequenceNumber) {
-    XdrInt64.encode(stream, encodedSequenceNumber._sequenceNumber);
+    XdrBigInt64.encode(stream, encodedSequenceNumber._sequenceNumber);
   }
 
   static XdrSequenceNumber decode(XdrDataInputStream stream) {
-    return XdrSequenceNumber(XdrInt64.decode(stream));
+    return XdrSequenceNumber(XdrBigInt64.decode(stream));
   }
 }
 
diff --git a/lib/src/xdr/xdr_transaction.dart b/lib/src/xdr/xdr_transaction.dart
index ee8d613..3928ee3 100644
--- a/lib/src/xdr/xdr_transaction.dart
+++ b/lib/src/xdr/xdr_transaction.dart
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a license that can be
 // found in the LICENSE file.
 
+import 'package:stellar_flutter_sdk/stellar_flutter_sdk.dart';
+
 import 'xdr_type.dart';
 import 'xdr_data_io.dart';
 import 'xdr_signing.dart';
@@ -2193,9 +2195,9 @@ class XdrPreconditionsV2 {
   XdrLedgerBounds? get ledgerBounds => this._ledgerBounds;
   set ledgerBounds(XdrLedgerBounds? value) => this._ledgerBounds = value;
 
-  XdrUint64? _sequenceNumber;
-  XdrUint64? get sequenceNumber => this._sequenceNumber;
-  set sequenceNumber(XdrUint64? value) => this._sequenceNumber = value;
+  XdrBigInt64? _sequenceNumber;
+  XdrBigInt64? get sequenceNumber => this._sequenceNumber;
+  set sequenceNumber(XdrBigInt64? value) => this._sequenceNumber = value;
 
   XdrUint64 _minSeqAge;
   XdrUint64 get minSeqAge => this._minSeqAge;
@@ -2225,7 +2227,7 @@ class XdrPreconditionsV2 {
 
     if (encoded.sequenceNumber != null) {
       stream.writeInt(1);
-      XdrUint64.encode(stream, encoded.sequenceNumber!);
+      XdrBigInt64.encode(stream, encoded.sequenceNumber!);
     } else {
       stream.writeInt(0);
     }
@@ -2242,7 +2244,7 @@ class XdrPreconditionsV2 {
   static XdrPreconditionsV2 decode(XdrDataInputStream stream) {
     XdrTimeBounds? tb;
     XdrLedgerBounds? lb;
-    XdrUint64? sqN;
+    XdrBigInt64? sqN;
 
     int timeBoundsPresent = stream.readInt();
     if (timeBoundsPresent != 0) {
@@ -2256,7 +2258,7 @@ class XdrPreconditionsV2 {
 
     int sequenceNumberPresent = stream.readInt();
     if (sequenceNumberPresent != 0) {
-      sqN = XdrUint64.decode(stream);
+      sqN = XdrBigInt64.decode(stream);
     }
 
     XdrUint64 minSA = XdrUint64.decode(stream);
diff --git a/pubspec.yaml b/pubspec.yaml
index 44fe0a8..467d005 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: stellar_flutter_sdk
 description: A stellar blockchain sdk that query's horizon, build, signs and submits transactions to the stellar network.
-version: 1.8.2
+version: 1.8.3
 homepage: https://github.com/Soneso/stellar_flutter_sdk
 
 environment:
diff --git a/test/account_test.dart b/test/account_test.dart
index 12f3b5c..50089f2 100644
--- a/test/account_test.dart
+++ b/test/account_test.dart
@@ -14,7 +14,7 @@ void main() {
     String accountAId = keyPairA.accountId;
     await FriendBot.fundTestAccount(accountAId);
     AccountResponse accountA = await sdk.accounts.account(keyPairA.accountId);
-    int seqNum = accountA.sequenceNumber;
+    BigInt seqNum = accountA.sequenceNumber;
 
     KeyPair keyPairB = KeyPair.random();
 
@@ -245,10 +245,10 @@ void main() {
     await FriendBot.fundTestAccount(accountId);
 
     AccountResponse account = await sdk.accounts.account(accountId);
-    int startSequence = account.sequenceNumber;
+    BigInt startSequence = account.sequenceNumber;
 
     BumpSequenceOperation bumpSequenceOperation =
-        BumpSequenceOperationBuilder(startSequence + 10).build();
+        BumpSequenceOperationBuilder(startSequence + BigInt.from(10)).build();
 
     Transaction transaction =
         TransactionBuilder(account).addOperation(bumpSequenceOperation).build();
@@ -261,7 +261,7 @@ void main() {
 
     account = await sdk.accounts.account(accountId);
 
-    assert(startSequence + 10 == account.sequenceNumber);
+    assert(startSequence + BigInt.from(10) == account.sequenceNumber);
 
     // test operation & effects responses can be parsed
     var operationsPage = await sdk.operations.forAccount(accountId).execute();
diff --git a/test/examples_test.dart b/test/examples_test.dart
index 7fb3b32..f8c169d 100644
--- a/test/examples_test.dart
+++ b/test/examples_test.dart
@@ -525,10 +525,10 @@ void main() {
     AccountResponse account = await sdk.accounts.account(accountId);
 
     // Remember current sequence number.
-    int startSequence = account.sequenceNumber;
+    BigInt startSequence = account.sequenceNumber;
 
     // Prepare the bump sequence operation to bump the sequence number to current + 10.
-    BumpSequenceOperationBuilder bumpSequenceOpB = BumpSequenceOperationBuilder(startSequence + 10);
+    BumpSequenceOperationBuilder bumpSequenceOpB = BumpSequenceOperationBuilder(startSequence + BigInt.from(10));
 
     // Prepare the transaction.
     Transaction transaction =
@@ -544,7 +544,7 @@ void main() {
     account = await sdk.accounts.account(accountId);
 
     // Check that the  sequence number has correctly been bumped.
-    if (startSequence + 10 == account.sequenceNumber) {
+    if (startSequence + BigInt.from(10) == account.sequenceNumber) {
       print("success");
     } else {
       print("failed");
diff --git a/test/payload_signer_test.dart b/test/payload_signer_test.dart
index 8eb9151..51acadb 100644
--- a/test/payload_signer_test.dart
+++ b/test/payload_signer_test.dart
@@ -70,7 +70,7 @@ void main() {
 
   test('test tx preconditions convert to xdr', () async {
     TransactionPreconditions cond = TransactionPreconditions();
-    cond.minSeqNumber = 91891891;
+    cond.minSeqNumber = BigInt.from(91891891);
     cond.minSeqAge = 181811;
     cond.minSeqLedgerGap = 1991;
     LedgerBounds lb = LedgerBounds(100, 100000);
diff --git a/test/payments_test.dart b/test/payments_test.dart
index 7c3848f..e2a38f7 100644
--- a/test/payments_test.dart
+++ b/test/payments_test.dart
@@ -94,7 +94,7 @@ void main() {
         await sdk.submitTransaction(transaction);
     assert(response.success);
     TestUtils.resultDeAndEncodingTest(transaction, response);
-    int testSeqNr = accountA.sequenceNumber;
+    BigInt testSeqNr = accountA.sequenceNumber;
 
     TransactionPreconditions precond = TransactionPreconditions();
     precond.timeBounds = new TimeBounds(1652110741, 1752110741);
diff --git a/test/sep0010_test.dart b/test/sep0010_test.dart
index 93f751c..f22e01c 100644
--- a/test/sep0010_test.dart
+++ b/test/sep0010_test.dart
@@ -111,7 +111,7 @@ void main() {
   }
 
   String requestChallengeSuccess(String accountId, [int? memo]) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(validSecondManageDataOp())
@@ -124,7 +124,7 @@ void main() {
   }
 
   String requestChallengeInvalidSequenceNumber(String accountId) {
-    final transactionAccount = Account(serverAccountId, 2803983);
+    final transactionAccount = Account(serverAccountId, BigInt.from(2803983));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(validSecondManageDataOp())
@@ -137,7 +137,7 @@ void main() {
   }
 
   String requestChallengeInvalidFirstOpSourceAccount() {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(
             serverAccountId)) // invalid because must be client account id
@@ -151,7 +151,7 @@ void main() {
   }
 
   String requestChallengeInvalidSecondOpSourceAccount(String accountId) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(secondManageDataOpInvalidSourceAccount())
@@ -164,7 +164,7 @@ void main() {
   }
 
   String requestChallengeInvalidClientDomainOpSourceAccount(String accountId) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(validSecondManageDataOp())
@@ -181,7 +181,7 @@ void main() {
     String accountId,
     String clientDomainAccountId,
   ) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(validSecondManageDataOp())
@@ -195,7 +195,7 @@ void main() {
   }
 
   String requestChallengeInvalidHomeDomain(String accountId) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(invalidHomeDomainOp(accountId))
         .addOperation(validSecondManageDataOp())
@@ -208,7 +208,7 @@ void main() {
   }
 
   String requestChallengeInvalidWebAuth(String accountId) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(invalidWebAuthOp())
@@ -221,7 +221,7 @@ void main() {
   }
 
   String requestChallengeInvalidTimeBounds(String accountId) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(validSecondManageDataOp())
@@ -234,7 +234,7 @@ void main() {
   }
 
   String requestChallengeInvalidOperationType(String accountId) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(validSecondManageDataOp())
@@ -251,7 +251,7 @@ void main() {
   }
 
   String requestChallengeInvalidSignature(String accountId) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(validSecondManageDataOp())
@@ -265,7 +265,7 @@ void main() {
   }
 
   String requestChallengeInvalidMemoType(String accountId) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(validSecondManageDataOp())
@@ -278,7 +278,7 @@ void main() {
   }
 
   String requestChallengeInvalidMemoValue(String accountId) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(validSecondManageDataOp())
@@ -291,7 +291,7 @@ void main() {
   }
 
   String requestChallengeMultipleSignature(String accountId) {
-    final transactionAccount = Account(serverAccountId, -1);
+    final transactionAccount = Account(serverAccountId, BigInt.from(-1));
     final Transaction transaction = new TransactionBuilder(transactionAccount)
         .addOperation(validFirstManageDataOp(accountId))
         .addOperation(validSecondManageDataOp())
diff --git a/test/sep0011_test.dart b/test/sep0011_test.dart
index 5205f40..7d80859 100644
--- a/test/sep0011_test.dart
+++ b/test/sep0011_test.dart
@@ -526,7 +526,7 @@ feeBump.signatures[0].signature: 085a2ee61be0d5bc2c2c7c7e90cc4c921febfe25aa54b6e
   test('fee bump transaction to txrep', () {
     KeyPair keyPairA = KeyPair.random();
     String accountAId = keyPairA.accountId;
-    Account a = Account(accountAId, 1102902109201);
+    Account a = Account(accountAId, BigInt.from(1102902109201));
 
     KeyPair keyPairB = KeyPair.random();
     String accountBId = keyPairB.accountId;
@@ -619,7 +619,7 @@ feeBump.signatures[0].signature: 085a2ee61be0d5bc2c2c7c7e90cc4c921febfe25aa54b6e
         ManageDataOperationBuilder(key, valueBytes).build();
 
     BumpSequenceOperation bumpSequenceOperation =
-        BumpSequenceOperationBuilder(a.sequenceNumber + 10).build();
+        BumpSequenceOperationBuilder(a.sequenceNumber + BigInt.from(10)).build();
 
     Transaction transaction = new TransactionBuilder(a)
         .addTimeBounds(tb)