diff --git a/README.md b/README.md
index 16fa1d2..77e161e 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ npm i --save advent-of-code-client
 
 ## How to use
 
-Initializing the client:
+**Initializing the client:**
 
 ```javascript
 import { AocClient } from 'advent-of-code-client';
@@ -22,7 +22,7 @@ const client = new AocClient({
 });
 ```
 
-Fetching the puzzle input:
+**Fetching the puzzle input:**
 
 ```javascript
 const input = await client.getInput();
@@ -51,26 +51,31 @@ const part2 = (input) => {
 await client.run([part1, part2], true);
 ```
 
-Transforming inputs before they are returned from `.getInput()`. This can be especially useful if you are running your puzzle parts automatically. When using the `.setInputTransform(transform)` method, the input to each part function will be the transformed / parsed data.
+**Transforming inputs before they are returned from `.getInput()`:**
+
+This can be especially useful if you are running your puzzle parts automatically. When using the `inputTransform` option when creating the client, the input passed to each part function will be the transformed / parsed data.
 
 For convenience there are a couple of pre-defined transform functions for commonly used transformations (i.e. splitting data by lines). The pre-defined transform functions are exported as `transforms`:
 
 ```javascript
 import { transforms } from 'advent-of-code-client';
 
-client.setInputTransform(transforms.lines);
+const client = new AocClient({
+  ... // other options
+  inputTransform: transforms.lines // automatically split the input by lines
+});
 ```
 
 You can also specify your own transform function:
 
 ```javascript
-
-const myTransform = rawData => {
-  ... // transform data
-  return transformedData;
-}
-
-client.setInputTransform(myTransform);
+const client = new AocClient({
+  ... // other options
+  inputTransform: (rawData) => {
+    ... // transform data
+    return transformedData;
+  }
+});
 ```
 
 ## Authentication
diff --git a/src/AocClient.ts b/src/AocClient.ts
index ab1bbde..4ca2f0d 100644
--- a/src/AocClient.ts
+++ b/src/AocClient.ts
@@ -10,24 +10,33 @@ import type {
   Config,
   PartFn,
   Result,
-  TransformFn
+  TransformFn,
+  ClientOptions
 } from './AocClient.types';
 
 const getCacheKey = ({ year, day, token, part }: CacheKeyParams) =>
   `${year}:${day}:${token}:${part}`;
 
+const noopTransform = (input: string) => input;
 /**
  * A class that handles fetching input from and submitting answers to Advent Of Code.
  * Each instance of the class corresponds to a puzzle for a specific day and year based on the configuration.
  */
-class AocClient {
+class AocClient<TransformedInput extends any = string> {
   private config: Config;
   private cache: Cache;
-  private transform: TransformFn;
+  private transform: TransformFn<TransformedInput>;
   /**
-   * @param {object} config
+   * @param {object} options
    */
-  constructor({ year, day, token, useCache = true, debug = false }: Config) {
+  constructor({
+    year,
+    day,
+    token,
+    useCache = true,
+    debug = false,
+    inputTransform = noopTransform as TransformFn<TransformedInput>
+  }: ClientOptions<TransformedInput>) {
     if (
       !year ||
       Number.isNaN(year) ||
@@ -64,7 +73,12 @@ class AocClient {
       globalThis.aocDebug = true;
     }
     this.cache = new CacheConf();
-    this.transform = null;
+    if (typeof inputTransform !== 'function') {
+      throw new Error(
+        'Invalid inputTransform option, inputTransform must be a function'
+      );
+    }
+    this.transform = inputTransform;
   }
 
   private _hasCompletedPart(part: number) {
@@ -85,7 +99,7 @@ class AocClient {
     logger.log('Fetching input...');
     const input = await getInput(this.config, this.cache);
     const trimmedInput = input.trim();
-    return this.transform ? this.transform(trimmedInput) : trimmedInput;
+    return this.transform(trimmedInput);
   }
 
   /**
@@ -139,7 +153,9 @@ class AocClient {
    * @param {boolean} autoSubmit - when true the answers for each part will be submitted to Advent Of Code automatically, otherwise each answer will require confirmation before it will be submitted.
    */
   async run(
-    parts: [part1: PartFn] | [part1: PartFn, part2: PartFn],
+    parts:
+      | [part1: PartFn<TransformedInput>]
+      | [part1: PartFn<TransformedInput>, part2: PartFn<TransformedInput>],
     autoSubmit = false
   ) {
     if (!parts || !parts.length || parts.length > 2) {
@@ -215,12 +231,6 @@ class AocClient {
     }
     return Promise.resolve();
   }
-
-  setInputTransform(transform: TransformFn) {
-    if (typeof transform !== 'function')
-      throw new Error('transform must be a function');
-    this.transform = transform;
-  }
 }
 
 export default AocClient;
diff --git a/src/AocClient.types.ts b/src/AocClient.types.ts
index b29dec2..51126d9 100644
--- a/src/AocClient.types.ts
+++ b/src/AocClient.types.ts
@@ -23,6 +23,10 @@ export type Config = {
   debug?: boolean;
 };
 
+export type ClientOptions<TransformedInput = string> = Config & {
+  inputTransform?: TransformFn<TransformedInput>;
+};
+
 export type Cache = {
   get: (key: string, options?: { ignoreMaxAge?: boolean }) => any;
   set: (
@@ -36,8 +40,8 @@ export type Cache = {
   isExpired: (key: string) => boolean;
 };
 
-export type TransformFn = (input: string) => any;
+export type TransformFn<T> = (input: string) => T;
 
 export type Result = number | string;
 
-export type PartFn = (input: any) => Result;
+export type PartFn<T> = (input: T) => Result;