diff --git a/index.d.ts b/index.d.ts
index 7cf2bd7..0d1c8ac 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -7,16 +7,16 @@ import {LEVEL, MESSAGE, SPLAT} from 'triple-beam'
 
 export interface TransformableInfo {
   level: string;
-  message: any;
+  message: unknown;
   [LEVEL]?: string;
-  [MESSAGE]?: any;
-  [SPLAT]?: any;
-  [key: string | symbol]: any;
+  [MESSAGE]?: unknown;
+  [SPLAT]?: unknown;
+  [key: string | symbol]: unknown;
 }
 
-export type TransformFunction = (info: TransformableInfo, opts?: any) => TransformableInfo | boolean;
+export type TransformFunction = (info: TransformableInfo, opts?: unknown) => TransformableInfo | boolean;
 export type Colors = { [key: string]: string | string[] }; // tslint:disable-line interface-over-type-literal
-export type FormatWrap = (opts?: any) => Format;
+export type FormatWrap = (opts?: unknown) => Format;
 
 export class Format {
   constructor(opts?: object);
@@ -82,7 +82,7 @@ export interface JsonOptions {
   /**
    * A function that influences how the `info` is stringified.
    */
-  replacer?: (this: any, key: string, value: any) => any;
+  replacer?: (this: unknown, key: string, value: unknown) => unknown;
   /**
    * The number of white space used to format the json.
    */