diff --git a/src/scripts/PageLoad.ts b/src/scripts/PageLoad.ts
index 85742dc..78394c9 100644
--- a/src/scripts/PageLoad.ts
+++ b/src/scripts/PageLoad.ts
@@ -1,7 +1,7 @@
 export type HtmlReady = 'loading' | 'done' | 'error';
 
 export class PageLoad {
-  static MOTION_DELAY = 1200;
+  static readonly MOTION_DELAY = 1200;
 
   static documentState() {
     return document.readyState;
diff --git a/src/scripts/Portfolio.ts b/src/scripts/Portfolio.ts
index 151f14c..cf6b8aa 100644
--- a/src/scripts/Portfolio.ts
+++ b/src/scripts/Portfolio.ts
@@ -40,7 +40,7 @@ export class Portfolio {
   // re-appear everytime the url is updated (ex: via replaceState). I am
   // simply disabling this behaviour for now... but I may need to do a
   // user-agent sniff in order to work around it.
-  static SUPPORT_URL_UPDATES = false;
+  static readonly SUPPORT_URL_UPDATES = false;
 
   constructor(selectors?: Selectors, onScroll?: CustomScrollFn) {
     this.#selector = {
diff --git a/src/scripts/PwaServiceWorker.ts b/src/scripts/PwaServiceWorker.ts
index 21a5da9..8a3a087 100644
--- a/src/scripts/PwaServiceWorker.ts
+++ b/src/scripts/PwaServiceWorker.ts
@@ -9,7 +9,7 @@ type PwaReloadFn = ((reloadPage?: boolean) => Promise<void>) | undefined;
 export class PwaServiceWorker {
   // TODO: We probably want to initialize a global singleton
   // that gets imported and shared in various places.
-  static #tracker = new ToastTracker();
+  static readonly #tracker = new ToastTracker();
   static #refreshWorker: PwaReloadFn;
 
   static install() {
diff --git a/src/scripts/SecretEmail.ts b/src/scripts/SecretEmail.ts
index afe51b3..ad51993 100644
--- a/src/scripts/SecretEmail.ts
+++ b/src/scripts/SecretEmail.ts
@@ -6,8 +6,8 @@ const DEFAULT_CLASSNAMES = {
 };
 
 export class SecretEmail {
-  static defaultSecretClass = DEFAULT_CLASSNAMES.secret;
-  static defaultReplaceClass = DEFAULT_CLASSNAMES.replace;
+  static readonly defaultSecretClass = DEFAULT_CLASSNAMES.secret;
+  static readonly defaultReplaceClass = DEFAULT_CLASSNAMES.replace;
 
   readonly email: string;
   readonly secretClass: string;
diff --git a/src/scripts/ToastTracker.ts b/src/scripts/ToastTracker.ts
index 41df8c6..eb2487b 100644
--- a/src/scripts/ToastTracker.ts
+++ b/src/scripts/ToastTracker.ts
@@ -4,8 +4,8 @@ type AddArgs = ConstructorParameters<typeof ToastNotification>;
 
 // TODO: Add event for `count` change using `emitten`.
 export class ToastTracker {
-  static MAX_SIZE = 10;
-  static DISMISS_AFTER_MS = 9999;
+  static readonly MAX_SIZE = 10;
+  static readonly DISMISS_AFTER_MS = 9999;
 
   #portal: HTMLElement;
   #queue: Map<string, ToastNotification>;