diff --git a/src/constants/index.ts b/src/constants/index.ts
index c24b5a07ae..d3eab50bbf 100644
--- a/src/constants/index.ts
+++ b/src/constants/index.ts
@@ -21,11 +21,6 @@ export const COMMON_BASES = {
   [ChainId.KOVAN]: [WETH[ChainId.KOVAN]]
 }
 
-export const SUPPORTED_THEMES = {
-  DARK: 'DARK',
-  LIGHT: 'LIGHT'
-}
-
 const MAINNET_WALLETS = {
   INJECTED: {
     connector: injected,
diff --git a/src/theme/index.tsx b/src/theme/index.tsx
index 70eb87a064..32fe254fe0 100644
--- a/src/theme/index.tsx
+++ b/src/theme/index.tsx
@@ -8,8 +8,7 @@ import styled, {
 } from 'styled-components'
 import { AppDispatch, AppState } from '../state'
 import { updateUserDarkMode } from '../state/user/actions'
-import { getQueryParam, checkSupportedTheme } from '../utils'
-import { SUPPORTED_THEMES } from '../constants'
+import { getQueryParam } from '../utils'
 import { useIsDarkMode } from '../state/user/hooks'
 import { Text, TextProps } from 'rebass'
 import { Colors } from './styled'
@@ -122,11 +121,11 @@ export default function ThemeProvider({ children }: { children: React.ReactNode
   const userDarkMode = useSelector<AppState, boolean | null>(state => state.user.userDarkMode)
   const darkMode = useIsDarkMode()
 
-  const themeURL = checkSupportedTheme(getQueryParam(window.location, 'theme'))
+  const themeURL = getQueryParam(window.location, 'theme')
   const urlContainsDarkMode: boolean | null = themeURL
-    ? themeURL.toUpperCase() === SUPPORTED_THEMES.DARK
+    ? themeURL.toUpperCase() === 'DARK'
       ? true
-      : themeURL.toUpperCase() === SUPPORTED_THEMES.LIGHT
+      : themeURL.toUpperCase() === 'LIGHT'
       ? false
       : null
     : null
diff --git a/src/utils/index.test.ts b/src/utils/index.test.ts
index f959461e99..f8a13679d6 100644
--- a/src/utils/index.test.ts
+++ b/src/utils/index.test.ts
@@ -1,7 +1,15 @@
+import { BigNumber } from '@ethersproject/bignumber'
 import { AddressZero } from '@ethersproject/constants'
-import { TokenAmount, Token, ChainId } from '@uniswap/sdk'
+import { TokenAmount, Token, ChainId, Percent, JSBI } from '@uniswap/sdk'
 
-import { getEtherscanLink, calculateSlippageAmount } from '.'
+import {
+  getEtherscanLink,
+  calculateSlippageAmount,
+  isAddress,
+  shortenAddress,
+  calculateGasMargin,
+  basisPointsToPercent
+} from '.'
 
 describe('utils', () => {
   describe('#getEtherscanLink', () => {
@@ -11,6 +19,15 @@ describe('utils', () => {
     it('correct for address', () => {
       expect(getEtherscanLink(1, 'abc', 'address')).toEqual('https://etherscan.io/address/abc')
     })
+    it('unrecognized chain id defaults to mainnet', () => {
+      expect(getEtherscanLink(2, 'abc', 'address')).toEqual('https://etherscan.io/address/abc')
+    })
+    it('ropsten', () => {
+      expect(getEtherscanLink(3, 'abc', 'address')).toEqual('https://ropsten.etherscan.io/address/abc')
+    })
+    it('enum', () => {
+      expect(getEtherscanLink(ChainId.RINKEBY, 'abc', 'address')).toEqual('https://rinkeby.etherscan.io/address/abc')
+    })
   })
 
   describe('#calculateSlippageAmount', () => {
@@ -24,4 +41,59 @@ describe('utils', () => {
       expect(() => calculateSlippageAmount(tokenAmount, 10001)).toThrow()
     })
   })
+
+  describe('#isAddress', () => {
+    it('returns false if not', () => {
+      expect(isAddress('')).toBe(false)
+      expect(isAddress('0x0000')).toBe(false)
+      expect(isAddress(1)).toBe(false)
+      expect(isAddress({})).toBe(false)
+      expect(isAddress(undefined)).toBe(false)
+    })
+
+    it('returns the checksummed address', () => {
+      expect(isAddress('0xf164fc0ec4e93095b804a4795bbe1e041497b92a')).toBe('0xf164fC0Ec4E93095b804a4795bBe1e041497b92a')
+      expect(isAddress('0xf164fC0Ec4E93095b804a4795bBe1e041497b92a')).toBe('0xf164fC0Ec4E93095b804a4795bBe1e041497b92a')
+    })
+
+    it('succeeds even without prefix', () => {
+      expect(isAddress('f164fc0ec4e93095b804a4795bbe1e041497b92a')).toBe('0xf164fC0Ec4E93095b804a4795bBe1e041497b92a')
+    })
+    it('fails if too long', () => {
+      expect(isAddress('f164fc0ec4e93095b804a4795bbe1e041497b92a0')).toBe(false)
+    })
+  })
+
+  describe('#shortenAddress', () => {
+    it('throws on invalid address', () => {
+      expect(() => shortenAddress('abc')).toThrow("Invalid 'address'")
+    })
+
+    it('truncates middle characters', () => {
+      expect(shortenAddress('0xf164fc0ec4e93095b804a4795bbe1e041497b92a')).toBe('0xf164...b92a')
+    })
+
+    it('truncates middle characters even without prefix', () => {
+      expect(shortenAddress('f164fc0ec4e93095b804a4795bbe1e041497b92a')).toBe('0xf164...b92a')
+    })
+
+    it('renders checksummed address', () => {
+      expect(shortenAddress('0x2E1b342132A67Ea578e4E3B814bae2107dc254CC'.toLowerCase())).toBe('0x2E1b...54CC')
+    })
+  })
+
+  describe('#calculateGasMargin', () => {
+    it('adds 10%', () => {
+      expect(calculateGasMargin(BigNumber.from(1000)).toString()).toEqual('1100')
+      expect(calculateGasMargin(BigNumber.from(50)).toString()).toEqual('55')
+    })
+  })
+
+  describe('#basisPointsToPercent', () => {
+    it('converts basis points numbers to percents', () => {
+      expect(basisPointsToPercent(100).equalTo(new Percent(JSBI.BigInt(1), JSBI.BigInt(100)))).toBeTruthy()
+      expect(basisPointsToPercent(500).equalTo(new Percent(JSBI.BigInt(5), JSBI.BigInt(100)))).toBeTruthy()
+      expect(basisPointsToPercent(50).equalTo(new Percent(JSBI.BigInt(5), JSBI.BigInt(1000)))).toBeTruthy()
+    })
+  })
 })
diff --git a/src/utils/index.ts b/src/utils/index.ts
index 93fcadbe31..74030cfcd6 100644
--- a/src/utils/index.ts
+++ b/src/utils/index.ts
@@ -7,15 +7,16 @@ import { BigNumber } from '@ethersproject/bignumber'
 
 import { abi as IUniswapV2PairABI } from '@uniswap/v2-core/build/IUniswapV2Pair.json'
 import { abi as IUniswapV2Router01ABI } from '@uniswap/v2-periphery/build/IUniswapV2Router01.json'
-import { ROUTER_ADDRESS, SUPPORTED_THEMES } from '../constants'
+import { ROUTER_ADDRESS } from '../constants'
 
 import ERC20_ABI from '../constants/abis/erc20.json'
 import ERC20_BYTES32_ABI from '../constants/abis/erc20_bytes32.json'
-import { JSBI, Percent, TokenAmount } from '@uniswap/sdk'
+import { ChainId, JSBI, Percent, TokenAmount } from '@uniswap/sdk'
 
+// returns the checksummed address if the address is valid, otherwise returns false
 export function isAddress(value: any): string | false {
   try {
-    return getAddress(value.toLowerCase())
+    return getAddress(value)
   } catch {
     return false
   }
@@ -26,7 +27,7 @@ export enum ERROR_CODES {
   TOKEN_DECIMALS = 2
 }
 
-const ETHERSCAN_PREFIXES = {
+const ETHERSCAN_PREFIXES: { [chainId in ChainId]: string } = {
   1: '',
   3: 'ropsten.',
   4: 'rinkeby.',
@@ -34,12 +35,8 @@ const ETHERSCAN_PREFIXES = {
   42: 'kovan.'
 }
 
-export function getEtherscanLink(
-  networkId: 1 | 3 | 4 | 5 | 42 | string | number,
-  data: string,
-  type: 'transaction' | 'address'
-) {
-  const prefix = `https://${ETHERSCAN_PREFIXES[networkId] || ETHERSCAN_PREFIXES[1]}etherscan.io`
+export function getEtherscanLink(chainId: ChainId, data: string, type: 'transaction' | 'address'): string {
+  const prefix = `https://${ETHERSCAN_PREFIXES[chainId] || ETHERSCAN_PREFIXES[1]}etherscan.io`
 
   switch (type) {
     case 'transaction': {
@@ -89,22 +86,18 @@ export function getAllQueryParams(): QueryParams {
   }
 }
 
-export function checkSupportedTheme(themeName: string) {
-  if (themeName && themeName.toUpperCase() in SUPPORTED_THEMES) {
-    return themeName.toUpperCase()
-  }
-  return null
-}
-
+// shorten the checksummed version of the input address to have 0x + 4 characters at start and end
 export function shortenAddress(address: string, chars = 4): string {
-  if (!isAddress(address)) {
+  const parsed = isAddress(address)
+  if (!parsed) {
     throw Error(`Invalid 'address' parameter '${address}'.`)
   }
-  return `${address.substring(0, chars + 2)}...${address.substring(42 - chars)}`
+  return `${parsed.substring(0, chars + 2)}...${parsed.substring(42 - chars)}`
 }
 
+// add 10%
 export function calculateGasMargin(value: BigNumber): BigNumber {
-  return value.mul(BigNumber.from(10000).add(BigNumber.from(1000))).div(BigNumber.from(10000)) // add 10%
+  return value.mul(BigNumber.from(10000).add(BigNumber.from(1000))).div(BigNumber.from(10000))
 }
 
 // converts a basis points value to a sdk percent
diff --git a/yarn.lock b/yarn.lock
index 5032c9ea2b..dd85b22dc2 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -7205,7 +7205,7 @@ escape-html@~1.0.3:
   resolved "https://registry.yarnpkg.com/escape-html/-/escape-html-1.0.3.tgz#0258eae4d3d0c0974de1c169188ef0051d1d1988"
   integrity sha1-Aljq5NPQwJdN4cFpGI7wBR0dGYg=
 
-escape-string-regexp@2.0.0, escape-string-regexp@^2.0.0:
+escape-string-regexp@2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/escape-string-regexp/-/escape-string-regexp-2.0.0.tgz#a30304e99daa32e23b2fd20f51babd07cffca344"
   integrity sha512-UpzcLCXolUWcNu5HtVMHYdXJjArjsF9C0aNnquZYY4uW/Vu0miy5YoWvbV345HauVvcAUnpRuhMMcqTcGOY2+w==