diff --git a/package.json b/package.json
index db36a0b..99cb4d5 100644
--- a/package.json
+++ b/package.json
@@ -92,6 +92,7 @@
     "@glint/template": "^1.5.2",
     "@rollup/plugin-babel": "^6.0.4",
     "@tsconfig/ember": "^3.0.8",
+    "@types/rsvp": "^4.0.9",
     "babel-plugin-ember-template-compilation": "^2.2.5",
     "concurrently": "^9.0.1",
     "decorator-transforms": "^2.2.2",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 4cd00f0..4443a8f 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -66,6 +66,9 @@ importers:
       '@tsconfig/ember':
         specifier: ^3.0.8
         version: 3.0.10
+      '@types/rsvp':
+        specifier: ^4.0.9
+        version: 4.0.9
       babel-plugin-ember-template-compilation:
         specifier: ^2.2.5
         version: 2.3.0
diff --git a/rollup.config.mjs b/rollup.config.mjs
index 2ed031a..61eaae1 100644
--- a/rollup.config.mjs
+++ b/rollup.config.mjs
@@ -48,9 +48,8 @@ export default {
     // Ensure that .gjs files are properly integrated as Javascript
     addon.gjs(),
 
-    // @todo convert addon to TypeScript
-    // // Emit .d.ts declaration files
-    // addon.declarations('declarations'),
+    // Emit .d.ts declaration files
+    addon.declarations('declarations'),
 
     // addons are allowed to contain imports of .css files, which we want rollup
     // to leave alone and keep in the published output.
diff --git a/src/index.js b/src/index.js
deleted file mode 100644
index b5d083d..0000000
--- a/src/index.js
+++ /dev/null
@@ -1,2 +0,0 @@
-export { lookupValidator as default } from 'validated-changeset';
-export { setMessages } from './utils/messages.js';
diff --git a/src/index.ts b/src/index.ts
new file mode 100644
index 0000000..05f6033
--- /dev/null
+++ b/src/index.ts
@@ -0,0 +1,4 @@
+export { lookupValidator as default } from 'validated-changeset';
+export { setMessages } from './utils/messages.ts';
+
+export type { ValidatorMapFunc } from 'validated-changeset/types';
diff --git a/src/utils/handle-multiple-validations.js b/src/utils/handle-multiple-validations.ts
similarity index 100%
rename from src/utils/handle-multiple-validations.js
rename to src/utils/handle-multiple-validations.ts
diff --git a/src/utils/messages.js b/src/utils/messages.ts
similarity index 84%
rename from src/utils/messages.js
rename to src/utils/messages.ts
index 3239a26..845d0b5 100644
--- a/src/utils/messages.js
+++ b/src/utils/messages.ts
@@ -1,8 +1,10 @@
 import _Messages from 'ember-validators/messages';
 import { capitalize, dasherize } from '@ember/string';
 
-let cachedRef;
-let customMessages;
+type IMessages = Record<string, string>;
+
+let cachedRef: IMessages | undefined;
+let customMessages: IMessages | undefined;
 
 export const defaultMessages = Object.assign({}, _Messages, {
   // Blank and present are flipped in ember-validators. Need to flip them back here
@@ -39,17 +41,17 @@ export const defaultMessages = Object.assign({}, _Messages, {
  *
  * @return {Object}
  */
-export function getMessages() {
+export function getMessages(): object {
   if (cachedRef) {
     return cachedRef;
   }
 
   cachedRef = Object.assign({}, defaultMessages, customMessages);
 
-  return cachedRef;
+  return cachedRef as IMessages;
 }
 
-export function setMessages(messages) {
+export function setMessages(messages: IMessages) {
   customMessages = messages;
   cachedRef = undefined;
 }
diff --git a/src/utils/to-date.js b/src/utils/to-date.ts
similarity index 89%
rename from src/utils/to-date.js
rename to src/utils/to-date.ts
index 6e9ea9d..91d604b 100644
--- a/src/utils/to-date.js
+++ b/src/utils/to-date.ts
@@ -4,7 +4,9 @@
  * @returns {Date} the parsed date in the local time zone
  * @throws {TypeError} 1 argument required
  */
-export default function toDate(argument) {
+export default function toDate(
+  argument: Date | number | string | (() => Date | number),
+): Date {
   const argStr = Object.prototype.toString.call(argument);
 
   if (typeof argument === 'function') {
diff --git a/src/utils/validation-errors.js b/src/utils/validation-errors.ts
similarity index 87%
rename from src/utils/validation-errors.js
rename to src/utils/validation-errors.ts
index 84cc5ac..2b769a4 100644
--- a/src/utils/validation-errors.js
+++ b/src/utils/validation-errors.ts
@@ -7,10 +7,16 @@ import { get } from '@ember/object';
 
 import { assert } from '@ember/debug';
 import { getOwnConfig } from '@embroider/macros';
-import { getMessages } from './messages.js';
+import { getMessages } from './messages.ts';
+
+type IOwnConfig =
+  | undefined
+  | {
+      rawOutput: boolean;
+    };
 
 export default function buildMessage(key, result) {
-  let returnsRaw = getOwnConfig()?.rawOutput || false;
+  let returnsRaw = getOwnConfig<IOwnConfig>()?.rawOutput || false;
   let messages = getMessages();
 
   let description = messages.getDescriptionFor(key);
diff --git a/src/utils/with-defaults.js b/src/utils/with-defaults.ts
similarity index 100%
rename from src/utils/with-defaults.js
rename to src/utils/with-defaults.ts
diff --git a/src/utils/wrap.js b/src/utils/wrap.ts
similarity index 100%
rename from src/utils/wrap.js
rename to src/utils/wrap.ts
diff --git a/src/validators/confirmation.js b/src/validators/confirmation.ts
similarity index 91%
rename from src/validators/confirmation.js
rename to src/validators/confirmation.ts
index 261cd81..a2cdd44 100644
--- a/src/validators/confirmation.js
+++ b/src/validators/confirmation.ts
@@ -1,4 +1,4 @@
-import buildMessage from '../utils/validation-errors.js';
+import buildMessage from '../utils/validation-errors.ts';
 import evValidateConfirmation from 'ember-validators/confirmation';
 
 export default function validateConfirmation(options = {}) {
diff --git a/src/validators/date.js b/src/validators/date.ts
similarity index 92%
rename from src/validators/date.js
rename to src/validators/date.ts
index af1ae90..854d80b 100644
--- a/src/validators/date.js
+++ b/src/validators/date.ts
@@ -1,6 +1,6 @@
-import buildMessage from '../utils/validation-errors.js';
-import withDefaults from '../utils/with-defaults.js';
-import toDate from '../utils/to-date.js';
+import buildMessage from '../utils/validation-errors.ts';
+import withDefaults from '../utils/with-defaults.ts';
+import toDate from '../utils/to-date.ts';
 
 const errorFormat = 'MMM Do, YYYY';
 
diff --git a/src/validators/exclusion.js b/src/validators/exclusion.ts
similarity index 85%
rename from src/validators/exclusion.js
rename to src/validators/exclusion.ts
index fc27a65..886257c 100644
--- a/src/validators/exclusion.js
+++ b/src/validators/exclusion.ts
@@ -1,4 +1,4 @@
-import buildMessage from '../utils/validation-errors.js';
+import buildMessage from '../utils/validation-errors.ts';
 import evValidateExclusion from 'ember-validators/exclusion';
 
 export default function validateExclusion(options = {}) {
diff --git a/src/validators/format.js b/src/validators/format.ts
similarity index 87%
rename from src/validators/format.js
rename to src/validators/format.ts
index 5f442a5..928feee 100644
--- a/src/validators/format.js
+++ b/src/validators/format.ts
@@ -1,5 +1,5 @@
 import { isEmpty } from '@ember/utils';
-import buildMessage from '../utils/validation-errors.js';
+import buildMessage from '../utils/validation-errors.ts';
 import evValidateFormat from 'ember-validators/format';
 
 export default function validateFormat(options = {}) {
diff --git a/src/validators/inclusion.js b/src/validators/inclusion.ts
similarity index 85%
rename from src/validators/inclusion.js
rename to src/validators/inclusion.ts
index ca3f46d..c02d664 100644
--- a/src/validators/inclusion.js
+++ b/src/validators/inclusion.ts
@@ -1,4 +1,4 @@
-import buildMessage from '../utils/validation-errors.js';
+import buildMessage from '../utils/validation-errors.ts';
 import evValidateInclusion from 'ember-validators/inclusion';
 
 export default function validateInclusion(options = {}) {
diff --git a/src/validators/index.js b/src/validators/index.js
deleted file mode 100644
index 71a6b39..0000000
--- a/src/validators/index.js
+++ /dev/null
@@ -1,8 +0,0 @@
-export { default as validateDate } from './date.js';
-export { default as validatePresence } from './presence.js';
-export { default as validateLength } from './length.js';
-export { default as validateNumber } from './number.js';
-export { default as validateFormat } from './format.js';
-export { default as validateInclusion } from './inclusion.js';
-export { default as validateExclusion } from './exclusion.js';
-export { default as validateConfirmation } from './confirmation.js';
diff --git a/src/validators/index.ts b/src/validators/index.ts
new file mode 100644
index 0000000..a1adfd4
--- /dev/null
+++ b/src/validators/index.ts
@@ -0,0 +1,8 @@
+export { default as validateDate } from './date.ts';
+export { default as validatePresence } from './presence.ts';
+export { default as validateLength } from './length.ts';
+export { default as validateNumber } from './number.ts';
+export { default as validateFormat } from './format.ts';
+export { default as validateInclusion } from './inclusion.ts';
+export { default as validateExclusion } from './exclusion.ts';
+export { default as validateConfirmation } from './confirmation.ts';
diff --git a/src/validators/length.js b/src/validators/length.ts
similarity index 75%
rename from src/validators/length.js
rename to src/validators/length.ts
index a5ebc5f..9ecaf3b 100644
--- a/src/validators/length.js
+++ b/src/validators/length.ts
@@ -1,5 +1,5 @@
-import buildMessage from '../utils/validation-errors.js';
-import withDefaults from '../utils/with-defaults.js';
+import buildMessage from '../utils/validation-errors.ts';
+import withDefaults from '../utils/with-defaults.ts';
 import evValidateLength from 'ember-validators/length';
 
 export default function validateLength(options = {}) {
diff --git a/src/validators/number.js b/src/validators/number.ts
similarity index 78%
rename from src/validators/number.js
rename to src/validators/number.ts
index b7ecafa..6807bcd 100644
--- a/src/validators/number.js
+++ b/src/validators/number.ts
@@ -1,5 +1,5 @@
-import buildMessage from '../utils/validation-errors.js';
-import withDefaults from '../utils/with-defaults.js';
+import buildMessage from '../utils/validation-errors.ts';
+import withDefaults from '../utils/with-defaults.ts';
 import evValidateNumber from 'ember-validators/number';
 
 export default function validateNumber(options = {}) {
diff --git a/src/validators/presence.js b/src/validators/presence.ts
similarity index 95%
rename from src/validators/presence.js
rename to src/validators/presence.ts
index 0d9eadb..e53a623 100644
--- a/src/validators/presence.js
+++ b/src/validators/presence.ts
@@ -1,4 +1,4 @@
-import buildMessage from '../utils/validation-errors.js';
+import buildMessage from '../utils/validation-errors.ts';
 import evValidatePresence from 'ember-validators/presence';
 import { get } from '@ember/object';