diff --git a/src/ActionLink.tsx b/src/ActionLink.tsx
index b98fccb..ec9d4d6 100644
--- a/src/ActionLink.tsx
+++ b/src/ActionLink.tsx
@@ -1,4 +1,4 @@
-import React, {HTMLProps, SyntheticEvent, useCallback} from 'react';
+import {HTMLProps, SyntheticEvent, useCallback} from 'react';
 
 type HTMLAnchorProps = Omit<HTMLProps<HTMLAnchorElement>, 'href' | 'onClick'>;
 
diff --git a/src/App.tsx b/src/App.tsx
index 1f69e27..bbc10e1 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -1,4 +1,4 @@
-import React, {useCallback, useEffect, useMemo, useState} from 'react';
+import {useCallback, useEffect, useMemo, useState} from 'react';
 import base32Decode from 'base32-decode';
 import {NumberInput, TextInput} from './Input';
 import OTPOutput from './OTPOutput';
@@ -6,6 +6,7 @@ import Select from './Select';
 import Collapsible from './Collapsible';
 import ActionLink from './ActionLink';
 import {defaults, serializeState, deserializeState} from './state';
+import {HashAlgorithm} from './algorithms.tsx';
 
 function parseState() {
   if (window.location.hash.startsWith('#!')) {
@@ -78,7 +79,7 @@ function App() {
   );
 
   const setAlgorithm = useCallback(
-    (algorithm: string) => setState((state) => ({...state, algorithm})),
+    (algorithm: HashAlgorithm) => setState((state) => ({...state, algorithm})),
     [],
   );
 
@@ -107,7 +108,7 @@ function App() {
       <div className="totp-settings">
         <TextInput label="Secret key" value={secret} onChange={setSecret}
                    error={!validSecret && 'Secret must be a valid base32-encoded string'}/>
-        <progress class="totp-tick" value={validStep ? remaining : 0} max={validStep ? step : 0}/>
+        <progress className="totp-tick" value={validStep ? remaining : 0} max={validStep ? step : 0}/>
         {advanced ?
           <ActionLink onClick={hideAdvanced}>Hide advanced options</ActionLink> :
           <ActionLink onClick={showAdvanced}>Show advanced options</ActionLink>}
@@ -124,7 +125,7 @@ function App() {
           <button type="button" className="btn btn-secondary" onClick={onReset}>Reset</button>
         </Collapsible>
       </div>
-      {valid && <OTPOutput secret={decoded} offset={offset} algorithm={algorithm} digits={digits}/>}
+      {valid && decoded && <OTPOutput secret={decoded} offset={offset} algorithm={algorithm} digits={digits}/>}
     </div>
   );
 }
diff --git a/src/Collapsible.tsx b/src/Collapsible.tsx
index fe034fb..ad7ca25 100644
--- a/src/Collapsible.tsx
+++ b/src/Collapsible.tsx
@@ -1,4 +1,4 @@
-import React, {ReactNode, useEffect, useId} from 'react';
+import {ReactNode, useEffect, useId} from 'react';
 import {Collapse} from 'bootstrap';
 
 export default function Collapsible({children, show}: { children: ReactNode; show: boolean }) {
diff --git a/src/CopyButton.tsx b/src/CopyButton.tsx
index 80a3c9b..9a853f0 100644
--- a/src/CopyButton.tsx
+++ b/src/CopyButton.tsx
@@ -1,4 +1,4 @@
-import React, {useCallback, useEffect, useId, useState} from 'react';
+import {useCallback, useEffect, useId, useState} from 'react';
 import Copy from './copy.svg?react';
 import {Popover} from 'bootstrap';
 
diff --git a/src/Input.tsx b/src/Input.tsx
index e51e667..3ef56b6 100644
--- a/src/Input.tsx
+++ b/src/Input.tsx
@@ -1,4 +1,4 @@
-import React, {ReactNode, HTMLProps, useCallback, useId} from 'react';
+import {ChangeEvent, ReactNode, HTMLProps, useCallback, useId} from 'react';
 import classNames from 'classnames';
 
 type CommonProps = {
diff --git a/src/OTPOutput.tsx b/src/OTPOutput.tsx
index f4e71ea..561f666 100644
--- a/src/OTPOutput.tsx
+++ b/src/OTPOutput.tsx
@@ -1,4 +1,4 @@
-import React, {useMemo} from 'react';
+import {useMemo} from 'react';
 import {HOTP, HOTPOptions} from '@otplib/core';
 import {createDigest} from '@otplib/plugin-crypto-js';
 import classNames from 'classnames';
@@ -20,7 +20,7 @@ function OTPCode({code, delta}: { code: string; delta: number }) {
 }
 
 export default function OTPOutput({secret, offset, algorithm, digits}: {
-  secret: string;
+  secret: ArrayBuffer;
   offset: number;
   algorithm: HashAlgorithm;
   digits: number;
@@ -35,7 +35,12 @@ export default function OTPOutput({secret, offset, algorithm, digits}: {
     {[...Array(21).keys()].map((i) => {
       const delta = i - 10;
       const current = offset + delta;
-      return <OTPCode key={current} code={otp.generate(secret, current)} delta={delta}/>;
+      return <OTPCode key={current} code={otp.generate(
+        // they really wanted an ArrayBuffer or some similar binary type
+        // but misdeclared the type
+        secret as unknown as string,
+        current,
+      )} delta={delta}/>;
     })}
   </div>;
 }
diff --git a/src/Select.tsx b/src/Select.tsx
index 160a19b..efe308c 100644
--- a/src/Select.tsx
+++ b/src/Select.tsx
@@ -1,4 +1,4 @@
-import React, {ChangeEvent, ReactNode, useCallback, useId} from 'react';
+import {ChangeEvent, ReactNode, useCallback, useId} from 'react';
 
 export default function Select<T extends string>({label, options, value, onChange}: {
   label: ReactNode;
diff --git a/src/state.tsx b/src/state.tsx
index f2e5f39..c508926 100644
--- a/src/state.tsx
+++ b/src/state.tsx
@@ -1,4 +1,3 @@
-
 import {ALGORITHMS, HashAlgorithm} from './algorithms.tsx';
 
 export type State = {
@@ -16,7 +15,7 @@ export const defaults: State = {
 } as const;
 
 export function serializeState(state: State): string {
-  const values = ['secret', 'step', 'digits', 'algorithm'].map(
+  const values = (['secret', 'step', 'digits', 'algorithm'] as Array<keyof State>).map(
     (key) => state[key] !== defaults[key] ? encodeURIComponent(state[key]) : '',
   );
   while (values[values.length - 1] === '') {
@@ -31,6 +30,6 @@ export function deserializeState(data: string): State {
     secret: values[0] || defaults.secret,
     step: +values[1] || defaults.step,
     digits: +values[2] || defaults.digits,
-    algorithm: ALGORITHMS[values[3]] !== undefined ? values[3] : defaults.algorithm,
+    algorithm: values[3] in ALGORITHMS !== undefined ? values[3] as HashAlgorithm : defaults.algorithm,
   };
 }