diff --git a/deno.ts b/deno.ts
index ea42bced..138350f3 100644
--- a/deno.ts
+++ b/deno.ts
@@ -2,7 +2,7 @@
 // Main entrypoint for Deno.
 //
 // TODO: find reasonable replacement for require logic.
-import * as path from 'https://deno.land/std/path/mod.ts'
+import * as path from 'https://deno.land/std@0.159.0/path/mod.ts'
 import { camelCase, decamelize, looksLikeNumber } from './build/lib/string-utils.js'
 import { YargsParser } from './build/lib/yargs-parser.js'
 import type { Arguments, ArgsInput, Parser, Options, DetailedArguments } from './build/lib/yargs-parser-types.d.ts'
diff --git a/lib/index.ts b/lib/index.ts
index 3cc34257..8ca8c9de 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -39,6 +39,7 @@ const parser = new YargsParser({
   resolve,
   // TODO: figure  out a  way to combine ESM and CJS coverage, such  that
   // we can exercise all the lines below:
+  /* c8 ignore start */
   require: (path: string) => {
     if (typeof require !== 'undefined') {
       return require(path)
@@ -49,6 +50,7 @@ const parser = new YargsParser({
       throw Error('only .json config files are supported in ESM')
     }
   }
+  /* c8 ignore stop */
 })
 const yargsParser: Parser = function Parser (args: ArgsInput, opts?: Partial<Options>): Arguments {
   const result = parser.parse(args.slice(), opts)
diff --git a/package.json b/package.json
index decd0c3f..d10e8cae 100644
--- a/package.json
+++ b/package.json
@@ -51,6 +51,7 @@
   "author": "Ben Coe <ben@npmjs.com>",
   "license": "ISC",
   "devDependencies": {
+    "@rollup/plugin-typescript": "^8.5.0",
     "@types/chai": "^4.2.11",
     "@types/mocha": "^9.0.0",
     "@types/node": "^16.11.4",
@@ -68,11 +69,11 @@
     "rimraf": "^3.0.2",
     "rollup": "^2.22.1",
     "rollup-plugin-cleanup": "^3.1.1",
-    "rollup-plugin-ts": "^3.0.2",
     "serve": "^14.0.0",
     "standardx": "^7.0.0",
     "start-server-and-test": "^1.11.2",
     "ts-transform-default-export": "^1.0.2",
+    "tslib": "^2.4.1",
     "typescript": "^4.0.0"
   },
   "files": [
diff --git a/rollup.config.js b/rollup.config.js
index 15fd65db..9e36123c 100644
--- a/rollup.config.js
+++ b/rollup.config.js
@@ -1,5 +1,5 @@
 import cleanup from 'rollup-plugin-cleanup'
-import ts from 'rollup-plugin-ts'
+import ts from '@rollup/plugin-typescript'
 import transformDefaultExport from 'ts-transform-default-export'
 
 const output = {