diff --git a/types/papaparse/index.d.ts b/types/papaparse/index.d.ts
index 89f2efa639bde02..62c468f2a7c16fa 100644
--- a/types/papaparse/index.d.ts
+++ b/types/papaparse/index.d.ts
@@ -119,7 +119,7 @@ export interface ParseConfig<T = any> {
     chunk?(results: ParseResult<T>, parser: Parser): void; // default: undefined
     beforeFirstChunk?(chunk: string): string | void; // default: undefined
     transform?(value: string, field: string | number): any; // default: undefined
-    transformHeader?(header: string): string; // default: undefined
+    transformHeader?(header: string, index: number): string; // default: undefined
 }
 
 export interface UnparseConfig {
diff --git a/types/papaparse/papaparse-tests.ts b/types/papaparse/papaparse-tests.ts
index ea3249e8e783b44..4eacdb5ecb4bc6a 100644
--- a/types/papaparse/papaparse-tests.ts
+++ b/types/papaparse/papaparse-tests.ts
@@ -1,24 +1,15 @@
-
-
-import Papa = require("papaparse");
-import {
-    ParseConfig,
-    UnparseConfig,
-    UnparseObject,
-    ParseError,
-    ParseMeta,
-    ParseResult
-} from "papaparse";
-import { Readable } from "stream";
+import Papa = require('papaparse');
+import { ParseConfig, UnparseConfig, UnparseObject, ParseError, ParseMeta, ParseResult } from 'papaparse';
+import { Readable } from 'stream';
 
 /**
  * Parsing
  */
-var res = Papa.parse("3,3,3");
+var res = Papa.parse('3,3,3');
 
 res.errors[0].code;
 
-Papa.parse("3,3,3", {
+Papa.parse('3,3,3', {
     delimiter: ';',
     comments: false,
     trimHeaders: false,
@@ -26,11 +17,11 @@ Papa.parse("3,3,3", {
         p.abort();
         results.data.length;
     },
-    dynamicTyping: true
+    dynamicTyping: true,
 });
 
-Papa.parse("3,3,3", {
-    dynamicTyping: (field: string | number): boolean => /headerName/i.test(field.toString())
+Papa.parse('3,3,3', {
+    dynamicTyping: (field: string | number): boolean => /headerName/i.test(field.toString()),
 });
 
 Papa.parse('3,3,3', {
@@ -56,8 +47,8 @@ Papa.parse('4;4;4', {
 var file = new File(null, null, null);
 
 Papa.parse(file, {
-    transform: function(value, field) {},
-    transformHeader: function(header) {
+    transform: function (value, field) {},
+    transformHeader: function (header, index) {
         return header;
     },
     complete: function (a, b) {
@@ -67,14 +58,10 @@ Papa.parse(file, {
 });
 
 // .pipe to make sure it returns a stream
-Papa.parse(Papa.NODE_STREAM_INPUT, {
-}).pipe
+Papa.parse(Papa.NODE_STREAM_INPUT, {}).pipe;
 
-const readable = new Readable()
-const rows = [
-    "1,2,3",
-    "4,5,6"
-]
+const readable = new Readable();
+const rows = ['1,2,3', '4,5,6'];
 
 rows.forEach(r => {
     readable.push(r);
@@ -85,45 +72,55 @@ const papaStream: NodeJS.ReadWriteStream = Papa.parse(Papa.NODE_STREAM_INPUT);
 readable.pipe(papaStream);
 
 // generic
-Papa.parse<string>("a,b,c", {
-    step: function(a) {
-        a.data[0]
-    }
-})
-
-Papa.parse<string>("a,b,c", {
-    chunk: function(a) {
-        a.data[0]
-    }
-})
-
-Papa.parse<[string, string, string]>("a,b,c", {
-    complete: function(a) {
-        a.data[0][0]
-        a.data[0][1]
-        a.data[0][2]
-    }
-})
+Papa.parse<string>('a,b,c', {
+    step: function (a) {
+        a.data[0];
+    },
+});
+
+Papa.parse<string>('a,b,c', {
+    chunk: function (a) {
+        a.data[0];
+    },
+});
 
+Papa.parse<[string, string, string]>('a,b,c', {
+    complete: function (a) {
+        a.data[0][0];
+        a.data[0][1];
+        a.data[0][2];
+    },
+});
 
 /**
  * Unparsing
  */
 Papa.unparse([{ a: 1, b: 1, c: 1 }]);
-Papa.unparse([[1, 2, 3], [4, 5, 6]]);
+Papa.unparse([
+    [1, 2, 3],
+    [4, 5, 6],
+]);
 Papa.unparse({
-    fields: ["3"],
-    data: []
+    fields: ['3'],
+    data: [],
 });
 
 Papa.unparse([{ a: 1, b: 1, c: 1 }], { quotes: false });
 Papa.unparse([{ a: 1, b: 1, c: 1 }], { quotes: [false, true, true] });
-Papa.unparse([[1, 2, 3], [4, 5, 6]], { delimiter: "," });
-Papa.unparse({
-    fields: ["3"],
-    data: []
-}, { newline: "\n" });
-
+Papa.unparse(
+    [
+        [1, 2, 3],
+        [4, 5, 6],
+    ],
+    { delimiter: ',' },
+);
+Papa.unparse(
+    {
+        fields: ['3'],
+        data: [],
+    },
+    { newline: '\n' },
+);
 
 /**
  * Properties
@@ -134,7 +131,7 @@ Papa.LocalChunkSize;
 /**
  * Parser
  */
-var parser = new Papa.Parser({})
+var parser = new Papa.Parser({});
 parser.getCharIndex();
 parser.abort();
-parser.parse("", 0, false);
+parser.parse('', 0, false);