diff --git a/.eslintrc.json b/.eslintrc.json
index 3407a0a..22ba101 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -21,6 +21,7 @@
             "error"
         ],
         "semi": "off",
+        "@typescript-eslint/no-explicit-any": "error",
         "@typescript-eslint/semi": [
             "error",
             "always"
diff --git a/js/apple2io.ts b/js/apple2io.ts
index 783bb78..f1a059e 100644
--- a/js/apple2io.ts
+++ b/js/apple2io.ts
@@ -12,7 +12,7 @@ type Annunciators = Record<annunciator, boolean>;
 
 export interface Apple2IOState {
     annunciators: Annunciators;
-    cards: Array<any | null>;
+    cards: Array<unknown | null>;
 }
 
 export type SampleListener = (sample: number[]) => void;
@@ -93,7 +93,7 @@ export default class Apple2IO implements MemoryPages, Restorable<Apple2IOState>
         this._calcSampleRate();
     }
 
-    _debug(..._args: any[]) {
+    _debug(..._args: unknown[]) {
         // debug.apply(this, arguments);
     }
 
diff --git a/js/base64.ts b/js/base64.ts
index 4fc8e36..7a8566c 100644
--- a/js/base64.ts
+++ b/js/base64.ts
@@ -125,7 +125,7 @@ export function base64_decode(data: string | null | undefined): memory | undefin
 const DATA_URL_PREFIX = 'data:application/octet-stream;base64,';
 
 export function base64_json_parse(json: string) {
-    const reviver = (_key: string, value: any) => {
+    const reviver = (_key: string, value: unknown) => {
         if (typeof value ==='string' && value.startsWith(DATA_URL_PREFIX)) {
             return base64_decode(value.slice(DATA_URL_PREFIX.length));
         }
@@ -135,8 +135,8 @@ export function base64_json_parse(json: string) {
     return JSON.parse(json, reviver);
 }
 
-export function base64_json_stringify(json: any) {
-    const replacer = (_key: string, value: any) => {
+export function base64_json_stringify(json: unknown) {
+    const replacer = (_key: string, value: unknown) => {
         if (value instanceof Uint8Array) {
             return DATA_URL_PREFIX + base64_encode(value);
         }
diff --git a/js/cards/cffa.ts b/js/cards/cffa.ts
index 4751f1f..058a9ca 100644
--- a/js/cards/cffa.ts
+++ b/js/cards/cffa.ts
@@ -152,7 +152,7 @@ export default class CFFA implements Card, MassStorage, Restorable<CFFAState> {
 
     // Verbose debug method
 
-    private _debug(..._args: any[]) {
+    private _debug(..._args: unknown[]) {
         // debug.apply(this, arguments);
     }
 
diff --git a/js/cards/disk2.ts b/js/cards/disk2.ts
index 5e98557..a0d717b 100644
--- a/js/cards/disk2.ts
+++ b/js/cards/disk2.ts
@@ -393,7 +393,7 @@ export default class DiskII implements Card {
         this.initWorker();
     }
 
-    private debug(..._args: any[]) {
+    private debug(..._args: unknown[]) {
         // debug.apply(this, arguments);
     }
 
diff --git a/js/cards/langcard.ts b/js/cards/langcard.ts
index 76727f3..0d65f9e 100644
--- a/js/cards/langcard.ts
+++ b/js/cards/langcard.ts
@@ -43,7 +43,7 @@ export default class LanguageCard implements Card, Restorable<LanguageCardState>
         this.read2 = this.rom;
     }
 
-    private debug(..._args: any[]) {
+    private debug(..._args: unknown[]) {
         // debug.apply(null, args);
     }
 
diff --git a/js/cards/smartport.ts b/js/cards/smartport.ts
index b9b5278..8432af5 100644
--- a/js/cards/smartport.ts
+++ b/js/cards/smartport.ts
@@ -135,7 +135,7 @@ export default class SmartPort implements Card, MassStorage, Restorable<SmartPor
         }
     }
 
-    private debug(..._args: any[]) {
+    private debug(..._args: unknown[]) {
         // debug.apply(this, arguments);
     }
 
diff --git a/js/cards/thunderclock.ts b/js/cards/thunderclock.ts
index 6671f87..d34ac4f 100644
--- a/js/cards/thunderclock.ts
+++ b/js/cards/thunderclock.ts
@@ -35,7 +35,7 @@ export default class Thunderclock implements Card, Restorable<ThunderclockState>
     private bits: boolean[] = [];
     private command: byte = COMMANDS.REGHOLD;
 
-    private debug(..._args: any[]) {
+    private debug(..._args: unknown[]) {
         // debug.apply(this, arguments);
     }
 
diff --git a/js/cpu6502.ts b/js/cpu6502.ts
index 102da50..21b383e 100644
--- a/js/cpu6502.ts
+++ b/js/cpu6502.ts
@@ -147,7 +147,7 @@ type WriteFn = (val: byte) => void;
 type ReadAddrFn = (opts?: Opts) => word;
 type ImpliedFn = () => void;
 
-interface Instruction<T = any> {
+interface Instruction<T = unknown> {
     name: string;
     mode: Mode;
     op: (fn: T) => void;
diff --git a/js/formats/woz.ts b/js/formats/woz.ts
index 5e200ba..17057f4 100644
--- a/js/formats/woz.ts
+++ b/js/formats/woz.ts
@@ -191,7 +191,7 @@ export class MetaChunk  {
 }
 
 interface Chunks {
-    [key: string]: any;
+    [key: string]: unknown;
     info?: InfoChunk;
     tmap?: TMapChunk;
     trks?: TrksChunk;
diff --git a/js/mmu.ts b/js/mmu.ts
index c1bfee5..f214977 100644
--- a/js/mmu.ts
+++ b/js/mmu.ts
@@ -310,7 +310,7 @@ export default class MMU implements Memory, Restorable<MMUState> {
         this._iouDisable = true;
     }
 
-    _debug(..._args: any[]) {
+    _debug(..._args: unknown[]) {
         // debug.apply(this, _args);
     }
 
diff --git a/js/types.ts b/js/types.ts
index 99a5629..6df4a96 100644
--- a/js/types.ts
+++ b/js/types.ts
@@ -102,7 +102,7 @@ export interface Card extends Memory, Restorable {
 
 export type TapeData = Array<[duration: number, high: boolean]>;
 
-export interface Restorable<T = any> {
+export interface Restorable<T = unknown> {
     getState(): T;
     setState(state: T): void;
 }
diff --git a/js/ui/screen.ts b/js/ui/screen.ts
index 4ed928d..c7e1754 100644
--- a/js/ui/screen.ts
+++ b/js/ui/screen.ts
@@ -12,7 +12,7 @@ declare global {
         webkitIsFullScreen: boolean;
     }
     interface Element {
-        webkitRequestFullScreen: (options?: any) => void;
+        webkitRequestFullScreen: (options?: unknown) => void;
     }
 }
 export class Screen implements OptionHandler {
diff --git a/js/util.ts b/js/util.ts
index cd74996..51372af 100644
--- a/js/util.ts
+++ b/js/util.ts
@@ -45,7 +45,7 @@ export function bytify(ary: number[]): memory {
 }
 
 /** Writes to the console. */
-export function debug(...args: any[]): void {
+export function debug(...args: unknown[]): void {
     console.log.apply(console, args);
 }