diff --git a/CHANGELIST.md b/CHANGELIST.md
index 11e658c..47a80f5 100644
--- a/CHANGELIST.md
+++ b/CHANGELIST.md
@@ -4,6 +4,7 @@
 
 - [#488](https://github.com/nevware21/ts-async/issues/488) [CHORE] Drop Node.js 16 from CI matrix and add Node.js 24
   - Node.js 16 is end-of-life and is no longer supported by key tooling dependencies (for example `puppeteer` and `@pnpm/error` require Node.js >= 18)
+- [#499](https://github.com/nevware21/ts-async/issues/499) [BUG] Add the required ES Promise / Iterable / AsyncIterable libs to the package tsconfig and document the consumer ES2018 lib requirement
 
 # v0.5.5 Jan 5th, 2026
 
diff --git a/README.md b/README.md
index 635d022..3b3a773 100644
--- a/README.md
+++ b/README.md
@@ -101,6 +101,11 @@ Install the npm packare: `npm install @nevware21/ts-async --save`
 > "@nevware21/ts-async": ">= 0.5.5 < 2.x"
 > ```
 
+This package still targets ES5 at runtime, but its public TypeScript types use later built-in definitions such as `Promise`, `Iterable`, and `AsyncIterable`. If your project currently compiles with only ES5 libs, update your `tsconfig.json` to include a later ES lib, for example:
+
+- Browser / mixed environments: `"lib": ["ES2018", "DOM"]`
+- Node-only environments: `"lib": ["ES2018"]`
+
 And then just import the helpers and use them.
 
 ### Simple Examples
diff --git a/lib/tsconfig.es6.json b/lib/tsconfig.es6.json
index e079dfa..9976723 100644
--- a/lib/tsconfig.es6.json
+++ b/lib/tsconfig.es6.json
@@ -1,7 +1,12 @@
 {
     "extends": "./tsconfig.base.json",
     "compilerOptions": {
+        "lib": [
+            "dom",
+            "es6",
+            "es2018.asynciterable"
+        ],
         "target": "es6",
         "outDir": "./build/es6"
     }
-}
\ No newline at end of file
+}
diff --git a/lib/tsconfig.json b/lib/tsconfig.json
index 6b9580d..b8f9fe8 100644
--- a/lib/tsconfig.json
+++ b/lib/tsconfig.json
@@ -1,10 +1,16 @@
 {
     "extends": "./tsconfig.base.json",
     "compilerOptions": {
+        "lib": [
+            "dom",
+            "es2015.promise",
+            "es2015.iterable",
+            "es2018.asynciterable"
+        ],
         "target": "es5",
         "declaration": true,
         "declarationDir": "./build/types",
         "removeComments": false,
         "outDir": "./build/es5"
     }
-}
\ No newline at end of file
+}