diff --git a/src/models/ProofsStore.ts b/src/models/ProofsStore.ts
index 6eb4bfe9..0431eb82 100644
--- a/src/models/ProofsStore.ts
+++ b/src/models/ProofsStore.ts
@@ -5,6 +5,7 @@ import {
     flow,
     isAlive,
   } from 'mobx-state-tree'
+  import { Amount } from '@cashu/cashu-ts'
   import { withSetPropAction } from './helpers/withSetPropAction'
   import { ProofModel, Proof, ProofRecord, ProofState } from './Proof'
   import { TransactionData, TransactionStatus } from './Transaction'
@@ -588,7 +589,7 @@ import {
                     } else {
                         const node = ProofModel.create({
                             ...proof,
-                            amount: Number(proof.amount),
+                            amount: Amount.from(proof.amount as any).toNumber(),
                             mintUrl: commitMintUrl,
                             tId: group.tId,
                             unit: reservation.unit,
diff --git a/src/screens/NfcPayScreen.tsx b/src/screens/NfcPayScreen.tsx
index c3229c48..60096860 100644
--- a/src/screens/NfcPayScreen.tsx
+++ b/src/screens/NfcPayScreen.tsx
@@ -596,7 +596,7 @@ export const NfcPayScreen = observer(function NfcPayScreen({ route }: Props) {
         log.trace('[handlePaymentRequest] decoded Cashu payment request', { pr })
 
         // Validate basics
-        if (!pr.amount || Number(pr.amount) <= 0) {
+        if (!pr.amount || pr.amount.toNumber() <= 0) {
             throw new AppError(Err.VALIDATION_ERROR, 'Payment request has no valid amount')
         }
 
@@ -616,7 +616,7 @@ export const NfcPayScreen = observer(function NfcPayScreen({ route }: Props) {
         // setEncodedCashuPaymentRequest(encoded)
         if (pr.description) setMemo(pr.description)
 
-        const requiredAmount = Number(pr.amount)
+        const requiredAmount = pr.amount.toNumber()
         const eligibleBalances = await getEligibleMintBalancesForCashu(pr, requiredAmount, unit)
 
         if (eligibleBalances.length === 0) {
diff --git a/src/screens/SendScreen.tsx b/src/screens/SendScreen.tsx
index 5c1ed544..bc833e0d 100644
--- a/src/screens/SendScreen.tsx
+++ b/src/screens/SendScreen.tsx
@@ -625,7 +625,7 @@ export const SendScreen = observer(function SendScreen({ route }: Props) {
                         setIsCashuPrWithDesc(true)
                     }
 
-                    const prAmount = pr.amount ? Number(pr.amount) : undefined
+                    const prAmount = pr.amount ? pr.amount.toNumber() : undefined
 
                     if (prAmount) {
                         setAmountToSend(`${numbro(prAmount / getCurrency(unitRef.current).precision).format({
diff --git a/src/services/cashu/cashuUtils.ts b/src/services/cashu/cashuUtils.ts
index d3c6d227..c2fcd09e 100644
--- a/src/services/cashu/cashuUtils.ts
+++ b/src/services/cashu/cashuUtils.ts
@@ -38,11 +38,20 @@ const isObj = function(v: unknown): v is object {
   return typeof v === 'object'
 }
 
+/**
+ * An amount as a number. cashu-ts (4.x) types proof, token and payment-request
+ * amounts as `Amount` objects, while our own models hold plain numbers; `Number()`
+ * on an `Amount` is deprecated and throws in cashu-ts v5.
+ */
+const toNumberAmount = function(amount: number | Amount | bigint | string): number {
+  return typeof amount === 'number' ? amount : Amount.from(amount).toNumber()
+}
+
 /**
  * Sum the amounts of an array of proofs
  */
 const sumProofs = function(proofs: CashuProof[]): number {
-  return proofs.reduce((acc: number, proof: CashuProof) => acc + Number(proof.amount), 0)
+  return proofs.reduce((acc: number, proof: CashuProof) => acc + toNumberAmount(proof.amount as any), 0)
 }
 
 const CASHU_URI_PREFIXES = [
@@ -839,6 +848,7 @@ export const CashuUtils = {
     extractEncodedCashuPaymentRequest,
     getProofsAmount,
     getMintsFromToken,
+    toNumberAmount,
     findExactMatch,
     findMinExcess,
     getProofsToSend,
diff --git a/src/services/db/reservationsRepo.ts b/src/services/db/reservationsRepo.ts
index e04aac92..94941f3f 100644
--- a/src/services/db/reservationsRepo.ts
+++ b/src/services/db/reservationsRepo.ts
@@ -1,4 +1,5 @@
 import {isAlive} from 'mobx-state-tree'
+import {Amount} from '@cashu/cashu-ts'
 import {Proof, ProofState} from '../../models/Proof'
 import {CashuProof} from '../cashu/cashuUtils'
 import {TransactionStatus} from '../../models/Transaction'
@@ -225,7 +226,7 @@ export const commitReservation = function (
         // binding can't bind non-primitive objects to an INTEGER column and
         // would silently drop the row, leaving the proof in MST but absent
         // from the database (lost on the next restart).
-        const amount = typeof proof.amount === 'number' ? proof.amount : Number(proof.amount)
+        const amount = typeof proof.amount === 'number' ? proof.amount : Amount.from(proof.amount as any).toNumber()
         batch.push([
           `INSERT OR REPLACE INTO proofs (id, amount, secret, C, dleq_r, dleq_s, dleq_e, unit, tId, mintUrl, state, updatedAt)
            VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
diff --git a/src/services/wallet/operations/cashuPaymentRequestApi.ts b/src/services/wallet/operations/cashuPaymentRequestApi.ts
index b1990f28..7597925a 100644
--- a/src/services/wallet/operations/cashuPaymentRequestApi.ts
+++ b/src/services/wallet/operations/cashuPaymentRequestApi.ts
@@ -381,7 +381,7 @@ async function finalize(
         transactionId,
     )
 
-    const receivedAmount = receivedProofs.reduce((acc, p) => acc + Number(p.amount), 0)
+    const receivedAmount = CashuUtils.getProofsAmount(receivedProofs)
     const outputToken = getEncodedToken({
         mint: mintUrl,
         proofs: normalizeProofAmounts(receivedProofs),
diff --git a/src/services/wallet/operations/nostrOperations.ts b/src/services/wallet/operations/nostrOperations.ts
index 9b1dc908..c322c96f 100644
--- a/src/services/wallet/operations/nostrOperations.ts
+++ b/src/services/wallet/operations/nostrOperations.ts
@@ -140,7 +140,7 @@ const handleClaimTask = async function (params: {
 
         const result: TransactionTaskResult = await receiveTask(
             decodedToken,
-            Number(tokenInfo.amount),
+            tokenInfo.amount.toNumber(),
             tokenInfo.memo || 'Received to Lightning address',
             encodedToken,
         )
@@ -402,7 +402,7 @@ const handleReceivedEventTask = async function (encryptedEvent: NostrEvent): Pro
         if (incoming.type === IncomingDataType.CASHU) {
 
             const tokenInfo = getTokenMetadata(incoming.encoded)
-            const amountToReceive = Number(tokenInfo.amount)
+            const amountToReceive = tokenInfo.amount.toNumber()
             const memo = tokenInfo.memo || 'Received over Nostr'
             const {unit, mint: mintUrl} = tokenInfo
 
diff --git a/src/services/wallet/operations/onchainTopupOperationApi.ts b/src/services/wallet/operations/onchainTopupOperationApi.ts
index 351a3e34..6afedc8c 100644
--- a/src/services/wallet/operations/onchainTopupOperationApi.ts
+++ b/src/services/wallet/operations/onchainTopupOperationApi.ts
@@ -70,7 +70,7 @@ import {
     NUT20_RECOVERY_GAP_LIMIT,
 } from '../../cashu/nut20'
 import {capMintAmount, mintableAmount} from './onchainAmounts'
-import {CashuProof} from '../../cashu/cashuUtils'
+import {CashuProof, CashuUtils} from '../../cashu/cashuUtils'
 import {MintUnit} from '../currency'
 import {WalletUtils} from '../utils'
 import {sendTopupNotification} from '../notifications'
@@ -548,7 +548,7 @@ async function _mintAvailable(
         })
     }
 
-    const mintedAmount = proofs.reduce((acc, p) => acc + Number(p.amount), 0)
+    const mintedAmount = CashuUtils.getProofsAmount(proofs)
     const currentSpendable = proofsStore.getUnitBalance(unit)?.unitBalance ?? 0
     const balanceAfter = currentSpendable + mintedAmount
 
diff --git a/src/services/wallet/operations/receiveOperationApi.ts b/src/services/wallet/operations/receiveOperationApi.ts
index 6feca224..b3d91400 100644
--- a/src/services/wallet/operations/receiveOperationApi.ts
+++ b/src/services/wallet/operations/receiveOperationApi.ts
@@ -318,7 +318,7 @@ async function execute(prepared: PreparedReceiveData): Promise<CompletedTransact
         tx.id,
     )
 
-    const receivedAmount = proofs.reduce((acc, p) => acc + Number(p.amount), 0)
+    const receivedAmount = CashuUtils.getProofsAmount(proofs)
     const outputToken = getEncodedToken({
         mint: prepared.mintUrl,
         proofs: normalizeProofAmounts(proofs),
diff --git a/src/services/wallet/operations/topupOperationApi.ts b/src/services/wallet/operations/topupOperationApi.ts
index cc289a61..15c1253d 100644
--- a/src/services/wallet/operations/topupOperationApi.ts
+++ b/src/services/wallet/operations/topupOperationApi.ts
@@ -56,7 +56,7 @@ import {
     isPrepared,
     isReverted,
 } from '../../../models/TransactionStates'
-import {CashuProof} from '../../cashu/cashuUtils'
+import {CashuProof, CashuUtils} from '../../cashu/cashuUtils'
 import {LightningUtils} from '../../lightning/lightningUtils'
 import {MintUnit, formatCurrency, getCurrency} from '../currency'
 import {NostrEvent} from '../../nostrService'
@@ -533,7 +533,7 @@ async function _finalizePaid(tx: Transaction): Promise<CompletedTransaction> {
     })
 
     const currentSpendable = proofsStore.getUnitBalance(unit)?.unitBalance ?? 0
-    const proofsAmount = proofs.reduce((acc, p) => acc + Number(p.amount), 0)
+    const proofsAmount = CashuUtils.getProofsAmount(proofs)
     const balanceAfter = currentSpendable + proofsAmount
 
     const txData = _parseData(tx)
diff --git a/src/services/wallet/revertTask.ts b/src/services/wallet/revertTask.ts
index 282567ab..11652111 100644
--- a/src/services/wallet/revertTask.ts
+++ b/src/services/wallet/revertTask.ts
@@ -10,7 +10,7 @@ import { TransactionTaskResult } from '../walletService'
 import { ProofReservation } from './proofReservation'
 import { WalletUtils } from './utils'
 import { MintUnit } from './currency'
-import { Token, getEncodedToken, normalizeProofAmounts } from '@cashu/cashu-ts'
+import { Token, getEncodedToken, normalizeProofAmounts, sumProofs } from '@cashu/cashu-ts'
 
 const {
   mintsStore,
@@ -99,7 +99,7 @@ try {
     // simulated: the original pending proofs were PENDING (contribute 0 to
     // UNSPENT pool); moving them to SPENT changes nothing. The new fresh
     // proofs added as UNSPENT raise the spendable balance.
-    const receivedAmount = receivedProofs.reduce((sum, p) => sum + Number(p.amount), 0)
+    const receivedAmount = sumProofs(receivedProofs).toNumber()
     const currentSpendable = proofsStore.getUnitBalance(unit)?.unitBalance ?? 0
     const balanceAfter = currentSpendable + receivedAmount