diff --git a/yarn-project/aztec.js/src/fee/fee_juice_payment_method_with_claim.ts b/yarn-project/aztec.js/src/fee/fee_juice_payment_method_with_claim.ts
index 8d88c54999df..565825c66ef2 100644
--- a/yarn-project/aztec.js/src/fee/fee_juice_payment_method_with_claim.ts
+++ b/yarn-project/aztec.js/src/fee/fee_juice_payment_method_with_claim.ts
@@ -1,6 +1,6 @@
 import { type FunctionCall } from '@aztec/circuit-types';
 import { type AztecAddress, Fr, FunctionSelector } from '@aztec/circuits.js';
-import { FunctionType } from '@aztec/foundation/abi';
+import { FunctionType, U128 } from '@aztec/foundation/abi';
 import { ProtocolContractAddress } from '@aztec/protocol-contracts';
 import { getCanonicalFeeJuice } from '@aztec/protocol-contracts/fee-juice';
 
@@ -35,7 +35,7 @@ export class FeeJuicePaymentMethodWithClaim extends FeeJuicePaymentMethod {
         isStatic: false,
         args: [
           this.sender.toField(),
-          new Fr(this.claim.claimAmount),
+          ...new U128(this.claim.claimAmount).toFields(),
           this.claim.claimSecret,
           new Fr(this.claim.messageLeafIndex),
         ],
diff --git a/yarn-project/sequencer-client/src/tx_validator/gas_validator.ts b/yarn-project/sequencer-client/src/tx_validator/gas_validator.ts
index d02f4c0638f3..a7dcfa4c5e37 100644
--- a/yarn-project/sequencer-client/src/tx_validator/gas_validator.ts
+++ b/yarn-project/sequencer-client/src/tx_validator/gas_validator.ts
@@ -1,5 +1,6 @@
 import { type Tx, TxExecutionPhase, type TxValidationResult, type TxValidator } from '@aztec/circuit-types';
-import { type AztecAddress, type Fr, FunctionSelector, type GasFees } from '@aztec/circuits.js';
+import { type AztecAddress, Fr, FunctionSelector, type GasFees } from '@aztec/circuits.js';
+import { U128 } from '@aztec/foundation/abi';
 import { createLogger } from '@aztec/foundation/log';
 import { computeFeePayerBalanceStorageSlot, getExecutionRequestsByPhase } from '@aztec/simulator/server';
 
@@ -65,10 +66,26 @@ export class GasTxValidator implements TxValidator<Tx> {
     const feeLimit = tx.data.constants.txContext.gasSettings.getFeeLimit();
 
     // Read current balance of the feePayer
-    const initialBalance = await this.#publicDataSource.storageRead(
+    // TODO(#11285): Remove the 2 reads below with the commented out code.
+    // Uncomment below ######################
+    // const initialBalance = await this.#publicDataSource.storageRead(
+    //   this.#feeJuiceAddress,
+    //   computeFeePayerBalanceStorageSlot(feePayer),
+    // );
+    // Uncomment above ######################
+    // Remove the following ######################
+    const initialBalanceLowLimb = await this.#publicDataSource.storageRead(
       this.#feeJuiceAddress,
       computeFeePayerBalanceStorageSlot(feePayer),
     );
+    const initialBalanceHighLimb = await this.#publicDataSource.storageRead(
+      this.#feeJuiceAddress,
+      new Fr(computeFeePayerBalanceStorageSlot(feePayer).toBigInt() + 1n),
+    );
+    const initialBalance = new Fr(
+      U128.fromU64sLE(initialBalanceLowLimb.toBigInt(), initialBalanceHighLimb.toBigInt()).toInteger(),
+    );
+    // Remove the above ######################
 
     // If there is a claim in this tx that increases the fee payer balance in Fee Juice, add it to balance
     const setupFns = getExecutionRequestsByPhase(tx, TxExecutionPhase.SETUP);
@@ -85,7 +102,9 @@ export class GasTxValidator implements TxValidator<Tx> {
         !fn.callContext.isStaticCall,
     );
 
-    const balance = claimFunctionCall ? initialBalance.add(claimFunctionCall.args[2]) : initialBalance;
+    const balance = claimFunctionCall
+      ? initialBalance.add(new Fr(U128.fromFields(claimFunctionCall.args.slice(2, 4)).toInteger()))
+      : initialBalance;
     if (balance.lt(feeLimit)) {
       this.#log.warn(`Rejecting transaction due to not enough fee payer balance`, {
         feePayer,
diff --git a/yarn-project/simulator/src/client/client_execution_context.ts b/yarn-project/simulator/src/client/client_execution_context.ts
index 342fe8fdc651..0aec42dd945b 100644
--- a/yarn-project/simulator/src/client/client_execution_context.ts
+++ b/yarn-project/simulator/src/client/client_execution_context.ts
@@ -95,7 +95,7 @@ export class ClientExecutionContext extends ViewDataOracle {
     const args = this.executionCache.getPreimage(this.argsHash);
 
     if (args.length !== argumentsSize) {
-      throw new Error('Invalid arguments size');
+      throw new Error(`Invalid arguments size: expected ${argumentsSize}, got ${args.length}`);
     }
 
     const privateContextInputs = new PrivateContextInputs(