diff --git a/ui/app/components/ui/token-input/token-input.component.js b/ui/app/components/ui/token-input/token-input.component.js
index bb802db86..4d85ed4a5 100644
--- a/ui/app/components/ui/token-input/token-input.component.js
+++ b/ui/app/components/ui/token-input/token-input.component.js
@@ -80,6 +80,8 @@ export default class TokenInput extends PureComponent {
 
     const multiplier = Math.pow(10, Number(decimals || 0))
     const hexValue = multiplyCurrencies(decimalValue || 0, multiplier, {
+      multiplicandBase: 10,
+      multiplierBase: 10,
       toNumericBase: 'hex',
     })
 
diff --git a/ui/app/helpers/utils/confirm-tx.util.js b/ui/app/helpers/utils/confirm-tx.util.js
index 5d5f7b9c6..8ff39e498 100644
--- a/ui/app/helpers/utils/confirm-tx.util.js
+++ b/ui/app/helpers/utils/confirm-tx.util.js
@@ -39,19 +39,23 @@ export function getHexGasTotal({ gasLimit, gasPrice }) {
 }
 
 export function addEth(...args) {
-  return args.reduce((acc, base) => {
-    return addCurrencies(acc, base, {
+  return args.reduce((acc, ethAmount) => {
+    return addCurrencies(acc, ethAmount, {
       toNumericBase: 'dec',
       numberOfDecimals: 6,
+      aBase: 10,
+      bBase: 10,
     })
   })
 }
 
 export function addFiat(...args) {
-  return args.reduce((acc, base) => {
-    return addCurrencies(acc, base, {
+  return args.reduce((acc, fiatAmount) => {
+    return addCurrencies(acc, fiatAmount, {
       toNumericBase: 'dec',
       numberOfDecimals: 2,
+      aBase: 10,
+      bBase: 10,
     })
   })
 }
diff --git a/ui/app/helpers/utils/conversion-util.js b/ui/app/helpers/utils/conversion-util.js
index 94a322bfe..ca6bad62b 100644
--- a/ui/app/helpers/utils/conversion-util.js
+++ b/ui/app/helpers/utils/conversion-util.js
@@ -54,6 +54,11 @@ const baseChange = {
   BN: (n) => new BN(n.toString(16)),
 }
 
+// Utility function for checking base types
+const isValidBase = (base) => {
+  return Number.isInteger(base) && base > 1
+}
+
 /**
  * Defines the base type of numeric value
  * @typedef {('hex' | 'dec' | 'BN')} NumericBase
@@ -162,6 +167,10 @@ const conversionUtil = (
   })
 
 const getBigNumber = (value, base) => {
+  if (!isValidBase(base)) {
+    throw new Error('Must specificy valid base')
+  }
+
   // We don't include 'number' here, because BigNumber will throw if passed
   // a number primitive it considers unsafe.
   if (typeof value === 'string' || value instanceof BigNumber) {
@@ -173,6 +182,11 @@ const getBigNumber = (value, base) => {
 
 const addCurrencies = (a, b, options = {}) => {
   const { aBase, bBase, ...conversionOptions } = options
+
+  if (!isValidBase(aBase) || !isValidBase(bBase)) {
+    throw new Error('Must specify valid aBase and bBase')
+  }
+
   const value = getBigNumber(a, aBase).add(getBigNumber(b, bBase))
 
   return converter({
@@ -183,6 +197,11 @@ const addCurrencies = (a, b, options = {}) => {
 
 const subtractCurrencies = (a, b, options = {}) => {
   const { aBase, bBase, ...conversionOptions } = options
+
+  if (!isValidBase(aBase) || !isValidBase(bBase)) {
+    throw new Error('Must specify valid aBase and bBase')
+  }
+
   const value = getBigNumber(a, aBase).minus(getBigNumber(b, bBase))
 
   return converter({
@@ -194,6 +213,10 @@ const subtractCurrencies = (a, b, options = {}) => {
 const multiplyCurrencies = (a, b, options = {}) => {
   const { multiplicandBase, multiplierBase, ...conversionOptions } = options
 
+  if (!isValidBase(multiplicandBase) || !isValidBase(multiplierBase)) {
+    throw new Error('Must specify valid multiplicandBase and multiplierBase')
+  }
+
   const value = getBigNumber(a, multiplicandBase).times(
     getBigNumber(b, multiplierBase),
   )
diff --git a/ui/app/helpers/utils/conversion-util.test.js b/ui/app/helpers/utils/conversion-util.test.js
index 22436977a..34a7a5308 100644
--- a/ui/app/helpers/utils/conversion-util.test.js
+++ b/ui/app/helpers/utils/conversion-util.test.js
@@ -5,17 +5,26 @@ import { addCurrencies, conversionUtil } from './conversion-util'
 describe('conversion utils', function () {
   describe('addCurrencies()', function () {
     it('add whole numbers', function () {
-      const result = addCurrencies(3, 9)
+      const result = addCurrencies(3, 9, {
+        aBase: 10,
+        bBase: 10,
+      })
       assert.equal(result.toNumber(), 12)
     })
 
     it('add decimals', function () {
-      const result = addCurrencies(1.3, 1.9)
+      const result = addCurrencies(1.3, 1.9, {
+        aBase: 10,
+        bBase: 10,
+      })
       assert.equal(result.toNumber(), 3.2)
     })
 
     it('add repeating decimals', function () {
-      const result = addCurrencies(1 / 3, 1 / 9)
+      const result = addCurrencies(1 / 3, 1 / 9, {
+        aBase: 10,
+        bBase: 10,
+      })
       assert.equal(result.toNumber(), 0.4444444444444444)
     })
   })
diff --git a/ui/app/helpers/utils/token-util.js b/ui/app/helpers/utils/token-util.js
index 804b58b90..fa581f910 100644
--- a/ui/app/helpers/utils/token-util.js
+++ b/ui/app/helpers/utils/token-util.js
@@ -217,6 +217,10 @@ export function getTokenFiatAmount(
   const currentTokenToFiatRate = multiplyCurrencies(
     contractExchangeRate,
     conversionRate,
+    {
+      multiplicandBase: 10,
+      multiplierBase: 10,
+    },
   )
   const currentTokenInFiat = conversionUtil(tokenAmount, {
     fromNumericBase: 'dec',
diff --git a/ui/app/helpers/utils/transactions.util.js b/ui/app/helpers/utils/transactions.util.js
index 99e3bdf63..6dda958cc 100644
--- a/ui/app/helpers/utils/transactions.util.js
+++ b/ui/app/helpers/utils/transactions.util.js
@@ -152,9 +152,11 @@ export async function isSmartContractAddress(address) {
 }
 
 export function sumHexes(...args) {
-  const total = args.reduce((acc, base) => {
-    return addCurrencies(acc, base, {
+  const total = args.reduce((acc, hexAmount) => {
+    return addCurrencies(acc, hexAmount, {
       toNumericBase: 'hex',
+      aBase: 16,
+      bBase: 16,
     })
   })
 
diff --git a/ui/app/pages/send/send-content/send-amount-row/amount-max-button/amount-max-button.utils.js b/ui/app/pages/send/send-content/send-amount-row/amount-max-button/amount-max-button.utils.js
index 4c053bd96..39045a78e 100644
--- a/ui/app/pages/send/send-content/send-amount-row/amount-max-button/amount-max-button.utils.js
+++ b/ui/app/pages/send/send-content/send-amount-row/amount-max-button/amount-max-button.utils.js
@@ -12,8 +12,11 @@ export function calcMaxAmount({ balance, gasTotal, sendToken, tokenBalance }) {
     ? multiplyCurrencies(tokenBalance, multiplier, {
         toNumericBase: 'hex',
         multiplicandBase: 16,
+        multiplierBase: 10,
       })
     : subtractCurrencies(addHexPrefix(balance), addHexPrefix(gasTotal), {
         toNumericBase: 'hex',
+        aBase: 16,
+        bBase: 16,
       })
 }