diff --git a/package.json b/package.json
index 957262c4..f803f7a7 100644
--- a/package.json
+++ b/package.json
@@ -19,7 +19,7 @@
   "dependencies": {
     "@types/lodash": "^4.14.136",
     "@types/ws": "^3.2.0",
-    "bignumber.js": "^4.1.0",
+    "bignumber.js": "^9.0.0",
     "https-proxy-agent": "^3.0.0",
     "jsonschema": "1.2.2",
     "lodash": "^4.17.4",
diff --git a/src/common/hashes/index.ts b/src/common/hashes/index.ts
index 79117cd2..8ad11fba 100644
--- a/src/common/hashes/index.ts
+++ b/src/common/hashes/index.ts
@@ -93,7 +93,7 @@ export const computeTrustlineHash = (address1: string, address2: string, currenc
   const address1Hex = addressToHex(address1)
   const address2Hex = addressToHex(address2)
 
-  const swap = (new BigNumber(address1Hex, 16)).greaterThan(
+  const swap = (new BigNumber(address1Hex, 16)).isGreaterThan(
     new BigNumber(address2Hex, 16))
   const lowAddressHex = swap ? address2Hex : address1Hex
   const highAddressHex = swap ? address1Hex : address2Hex
diff --git a/src/common/utils.ts b/src/common/utils.ts
index 470262f9..e30ba650 100644
--- a/src/common/utils.ts
+++ b/src/common/utils.ts
@@ -83,7 +83,7 @@ function xrpToDrops(xrp: string | BigNumber): string {
       ` too many decimal places.`)
   }
 
-  return (new BigNumber(xrp)).times(1000000.0).floor().toString(10)
+  return (new BigNumber(xrp)).times(1000000.0).integerValue(BigNumber.ROUND_FLOOR).toString(10)
 }
 
 function toRippledAmount(amount: Amount): RippledAmount {
diff --git a/src/ledger/parse/account-order.ts b/src/ledger/parse/account-order.ts
index 997a7c5f..3b4e8d1f 100644
--- a/src/ledger/parse/account-order.ts
+++ b/src/ledger/parse/account-order.ts
@@ -17,7 +17,7 @@ export type FormattedAccountOrder = {
 // TODO: remove this function once rippled provides quality directly
 function computeQuality(takerGets, takerPays) {
   const quotient = new BigNumber(takerPays.value).dividedBy(takerGets.value)
-  return quotient.toDigits(16, BigNumber.ROUND_HALF_UP).toString()
+  return quotient.precision(16, BigNumber.ROUND_HALF_UP).toString()
 }
 
 // rippled 'account_offers' returns a different format for orders than 'tx'
diff --git a/src/ledger/parse/fields.ts b/src/ledger/parse/fields.ts
index 6d4d3bef..307d6fc2 100644
--- a/src/ledger/parse/fields.ts
+++ b/src/ledger/parse/fields.ts
@@ -8,7 +8,7 @@ function parseField(info, value) {
     return Buffer.from(value, 'hex').toString('ascii')
   }
   if (info.shift) {
-    return (new BigNumber(value)).shift(-info.shift).toNumber()
+    return (new BigNumber(value)).shiftedBy(-info.shift).toNumber()
   }
   return value
 }
diff --git a/src/ledger/parse/utils.ts b/src/ledger/parse/utils.ts
index 1f53504c..fe1cf83e 100644
--- a/src/ledger/parse/utils.ts
+++ b/src/ledger/parse/utils.ts
@@ -15,14 +15,14 @@ function adjustQualityForXRP(
   const denominatorShift = (takerGetsCurrency === 'XRP' ? -6 : 0)
   const shift = numeratorShift - denominatorShift
   return shift === 0 ? quality :
-    (new BigNumber(quality)).shift(shift).toString()
+    (new BigNumber(quality)).shiftedBy(shift).toString()
 }
 
 function parseQuality(quality?: number|null): number|undefined {
   if (typeof quality !== 'number') {
     return undefined
   }
-  return (new BigNumber(quality)).shift(-9).toNumber()
+  return (new BigNumber(quality)).shiftedBy(-9).toNumber()
 }
 
 function parseTimestamp(rippleTime?: number|null): string|undefined {
diff --git a/src/ledger/pathfind.ts b/src/ledger/pathfind.ts
index d4143569..652d76d3 100644
--- a/src/ledger/pathfind.ts
+++ b/src/ledger/pathfind.ts
@@ -73,7 +73,7 @@ function addDirectXrpPath(paths: RippledPathsResponse, xrpBalance: string
   // Add XRP "path" only if the source acct has enough XRP to make the payment
   const destinationAmount = paths.destination_amount
   // @ts-ignore: destinationAmount can be a currency amount object! Fix!
-  if ((new BigNumber(xrpBalance)).greaterThanOrEqualTo(destinationAmount)) {
+  if ((new BigNumber(xrpBalance)).isGreaterThanOrEqualTo(destinationAmount)) {
     paths.alternatives.unshift({
       paths_computed: [],
       source_amount: paths.destination_amount
diff --git a/src/transaction/settings.ts b/src/transaction/settings.ts
index c7d169cf..bc3a5787 100644
--- a/src/transaction/settings.ts
+++ b/src/transaction/settings.ts
@@ -62,7 +62,7 @@ function setTransactionFields(txJSON: utils.TransactionJSON, input: FormattedSet
  */
 
 function convertTransferRate(transferRate: number): number {
-  return (new BigNumber(transferRate)).shift(9).toNumber()
+  return (new BigNumber(transferRate)).shiftedBy(9).toNumber()
 }
 
 function formatSignerEntry(signer: WeightedSigner): object {
diff --git a/src/transaction/sign.ts b/src/transaction/sign.ts
index e3a6a112..af4dc5f7 100644
--- a/src/transaction/sign.ts
+++ b/src/transaction/sign.ts
@@ -183,7 +183,7 @@ function checkTxSerialization(serialized: string, tx: utils.TransactionJSON): vo
 function checkFee(api: RippleAPI, txFee: string): void {
   const fee = new BigNumber(txFee)
   const maxFeeDrops = xrpToDrops(api._maxFeeXRP)
-  if (fee.greaterThan(maxFeeDrops)) {
+  if (fee.isGreaterThan(maxFeeDrops)) {
     throw new utils.common.errors.ValidationError(
       `"Fee" should not exceed "${maxFeeDrops}". ` +
       'To use a higher fee, set `maxFeeXRP` in the RippleAPI constructor.'
diff --git a/src/transaction/trustline.ts b/src/transaction/trustline.ts
index 68153ba7..114d111c 100644
--- a/src/transaction/trustline.ts
+++ b/src/transaction/trustline.ts
@@ -9,7 +9,7 @@ import {
 import {RippleAPI} from '..'
 
 function convertQuality(quality) {
-  return (new BigNumber(quality)).shift(9).truncated().toNumber()
+  return (new BigNumber(quality)).shiftedBy(9).integerValue(BigNumber.ROUND_DOWN).toNumber()
 }
 
 function createTrustlineTransaction(account: string,
diff --git a/src/transaction/utils.ts b/src/transaction/utils.ts
index 6cc7a02d..f859ff3c 100644
--- a/src/transaction/utils.ts
+++ b/src/transaction/utils.ts
@@ -218,7 +218,7 @@ function prepareTransaction(txJSON: TransactionJSON, api: RippleAPI,
       instructions.signersCount + 1
     if (instructions.fee !== undefined) {
       const fee = new BigNumber(instructions.fee)
-      if (fee.greaterThan(api._maxFeeXRP)) {
+      if (fee.isGreaterThan(api._maxFeeXRP)) {
         return Promise.reject(new ValidationError(`Fee of ${fee.toString(10)} XRP exceeds ` +
           `max of ${api._maxFeeXRP} XRP. To use this fee, increase ` +
           '`maxFeeXRP` in the RippleAPI constructor.'))
diff --git a/test/api-test.ts b/test/api-test.ts
index c91585ab..ddf272c6 100644
--- a/test/api-test.ts
+++ b/test/api-test.ts
@@ -3636,7 +3636,7 @@ describe('RippleAPI', function () {
           .dividedBy(order.specification.quantity.value)
           .toString();
         }
-        assert((new BigNumber(rate)).greaterThanOrEqualTo(previousRate),
+        assert((new BigNumber(rate)).isGreaterThanOrEqualTo(previousRate),
           'Rates must be sorted from least to greatest: ' +
           rate + ' should be >= ' + previousRate);
         previousRate = rate;
@@ -3894,7 +3894,7 @@ describe('RippleAPI', function () {
           .dividedBy(order.specification.quantity.value)
           .toString();
         }
-        assert((new BigNumber(rate)).greaterThanOrEqualTo(previousRate),
+        assert((new BigNumber(rate)).isGreaterThanOrEqualTo(previousRate),
           'Rates must be sorted from least to greatest: ' +
           rate + ' should be >= ' + previousRate);
         previousRate = rate;
diff --git a/test/x-address-api-test.js b/test/x-address-api-test.js
index 20aba19f..157b3576 100644
--- a/test/x-address-api-test.js
+++ b/test/x-address-api-test.js
@@ -3437,7 +3437,7 @@ describe('X-address Usage', function () {
           .dividedBy(order.specification.quantity.value)
           .toString();
         }
-        assert((new BigNumber(rate)).greaterThanOrEqualTo(previousRate),
+        assert((new BigNumber(rate)).isGreaterThanOrEqualTo(previousRate),
           'Rates must be sorted from least to greatest: ' +
           rate + ' should be >= ' + previousRate);
         previousRate = rate;
@@ -3695,7 +3695,7 @@ describe('X-address Usage', function () {
           .dividedBy(order.specification.quantity.value)
           .toString();
         }
-        assert((new BigNumber(rate)).greaterThanOrEqualTo(previousRate),
+        assert((new BigNumber(rate)).isGreaterThanOrEqualTo(previousRate),
           'Rates must be sorted from least to greatest: ' +
           rate + ' should be >= ' + previousRate);
         previousRate = rate;
diff --git a/yarn.lock b/yarn.lock
index ad36ecec..779ec70f 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -568,10 +568,10 @@ bignumber.js@8.1.1:
   resolved "https://registry.yarnpkg.com/bignumber.js/-/bignumber.js-8.1.1.tgz#4b072ae5aea9c20f6730e4e5d529df1271c4d885"
   integrity sha512-QD46ppGintwPGuL1KqmwhR0O+N2cZUg8JG/VzwI2e28sM9TqHjQB10lI4QAaMHVbLzwVLLAwEglpKPViWX+5NQ==
 
-bignumber.js@^4.1.0:
-  version "4.1.0"
-  resolved "https://registry.yarnpkg.com/bignumber.js/-/bignumber.js-4.1.0.tgz#db6f14067c140bd46624815a7916c92d9b6c24b1"
-  integrity sha512-eJzYkFYy9L4JzXsbymsFn3p54D+llV27oTQ+ziJG7WFRheJcNZilgVXMG0LoZtlQSKBsJdWtLFqOD0u+U0jZKA==
+bignumber.js@^9.0.0:
+  version "9.0.0"
+  resolved "https://registry.yarnpkg.com/bignumber.js/-/bignumber.js-9.0.0.tgz#805880f84a329b5eac6e7cb6f8274b6d82bdf075"
+  integrity sha512-t/OYhhJ2SD+YGBQcjY8GzzDHEk9f3nerxjtfa6tlMXfe7frs/WozhvCNoGvpM0P3bNf3Gq5ZRMlGr5f3r4/N8A==
 
 binary-extensions@^1.0.0:
   version "1.13.1"