diff --git a/.npmignore b/.npmignore
index 30da0b7..bf07be4 100644
--- a/.npmignore
+++ b/.npmignore
@@ -2,6 +2,6 @@ src
 tsconfig.json
 rollup.config.ts
 jest.config.js
-.travis.yml
 size.txt
+.vscode
 
diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..55712c1
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+    "typescript.tsdk": "node_modules/typescript/lib"
+}
\ No newline at end of file
diff --git a/package.json b/package.json
index 85cdd66..89fcc11 100644
--- a/package.json
+++ b/package.json
@@ -13,6 +13,7 @@
     "test:debug:named": "node --inspect-brk node_modules/.bin/jest --runInBand --watch --testNamePattern",
     "lint": "eslint . --ext=js,ts",
     "lint:fix": "eslint . --ext=js,ts --fix",
+    "lint:tsc": "tsc --noEmit",
     "prepare": "npm run build",
     "prepublishOnly": "npm run test && npm run lint",
     "preversion": "npm run lint",
diff --git a/src/-private/change.ts b/src/-private/change.ts
index 3c112a0..ad8fae5 100644
--- a/src/-private/change.ts
+++ b/src/-private/change.ts
@@ -1,4 +1,3 @@
-/* import { IChange } from '../types'; */
 import isObject from '../utils/is-object';
 
 export const VALUE = Symbol('__value__');
@@ -20,3 +19,7 @@ export function getChangeValue(maybeChange: Change | unknown): any {
     return maybeChange[VALUE];
   }
 }
+
+export interface Changes {
+  [s: string]: any;
+}
diff --git a/src/-private/err.ts b/src/-private/err.ts
index de4e781..003837f 100644
--- a/src/-private/err.ts
+++ b/src/-private/err.ts
@@ -1,4 +1,4 @@
-import type { IErr, ValidationErr } from '../types';
+import type { ValidationErr } from '../types';
 
 export default class Err implements IErr<any> {
   value: any;
@@ -9,3 +9,18 @@ export default class Err implements IErr<any> {
     this.validation = validation;
   }
 }
+
+export interface IErr<T> {
+  value: T;
+  validation: ValidationErr | ValidationErr[];
+}
+
+export type Errors<T> = {
+  [s: string]: IErr<T>;
+};
+
+export type PublicErrors = {
+  key: string;
+  value: any;
+  validation: ValidationErr | ValidationErr[];
+}[];
\ No newline at end of file
diff --git a/src/index.ts b/src/index.ts
index 218ad4f..c2b2b02 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,8 +1,8 @@
-import Change, { getChangeValue, isChange } from './-private/change';
+import Change, { getChangeValue, isChange, type Changes } from './-private/change';
 import { getKeyValues, getKeyErrorValues } from './utils/get-key-values';
 import lookupValidator from './utils/validator-lookup';
 import { notifierForEvent } from './-private/evented';
-import Err from './-private/err';
+import Err, { type Errors, type IErr } from './-private/err';
 import { hasKey, pathInChanges } from './utils/has-key';
 import normalizeObject from './utils/normalize-object';
 import { hasChanges } from './utils/has-changes';
@@ -23,11 +23,8 @@ import getDeep, { getSubObject } from './utils/get-deep';
 import { objectToArray, arrayToObject } from './utils/array-object';
 
 import type {
-  Changes,
   Config,
   Content,
-  Errors,
-  IErr,
   IChangeset,
   INotifier,
   InternalMap,
diff --git a/src/types/index.ts b/src/types/index.ts
index ba8e0ba..e870030 100644
--- a/src/types/index.ts
+++ b/src/types/index.ts
@@ -61,19 +61,15 @@ export type ValidatorMap =
   | null
   | undefined;
 
-// https://github.com/microsoft/TypeScript/pull/26797
-/* export interface IChange { */
-/*   [s: symbol]: any; */
-/* } */
-export interface Changes {
-  [s: string]: any; //IChange;
-}
-
 export interface Content {
   save?: (...args: unknown[]) => unknown | undefined;
   [key: string]: any;
 }
 
+export interface Changes {
+  [s: string]: any;
+}
+
 export interface IErr<T> {
   value: T;
   validation: ValidationErr | ValidationErr[];