diff --git a/declaration.tsconfig.json b/declaration.tsconfig.json
new file mode 100644
index 0000000..c8d2a71
--- /dev/null
+++ b/declaration.tsconfig.json
@@ -0,0 +1,8 @@
+{
+	"extends": "./tsconfig",
+	"compilerOptions": {
+		"declaration": true,
+		"noEmit": false,
+		"emitDeclarationOnly": true
+	}
+}
diff --git a/index.js b/index.js
index 89f1b2c..aab476a 100644
--- a/index.js
+++ b/index.js
@@ -2,10 +2,14 @@
 const supportsColor = require('supports-color');
 const hasFlag = require('has-flag');
 
+/**
+@param {string} versionString
+@returns {{ major: number, minor: number, patch: number }}
+*/
 function parseVersion(versionString) {
 	if (/^\d{3,4}$/.test(versionString)) {
 		// Env var doesn't always use dots. example: 4601 => 46.1.0
-		const m = /(\d{1,2})(\d{2})/.exec(versionString);
+		const m = /(\d{1,2})(\d{2})/.exec(versionString) || [];
 		return {
 			major: 0,
 			minor: parseInt(m[1], 10),
@@ -21,11 +25,23 @@ function parseVersion(versionString) {
 	};
 }
 
+/**
+@param {{ isTTY?: boolean | undefined }} stream
+@returns {boolean}
+*/
 function supportsHyperlink(stream) {
-	const {env} = process;
-
-	if ('FORCE_HYPERLINK' in env) {
-		return !(env.FORCE_HYPERLINK.length > 0 && parseInt(env.FORCE_HYPERLINK, 10) === 0);
+	const {
+		CI,
+		FORCE_HYPERLINK,
+		NETLIFY,
+		TEAMCITY_VERSION,
+		TERM_PROGRAM,
+		TERM_PROGRAM_VERSION,
+		VTE_VERSION
+	} = process.env;
+
+	if (FORCE_HYPERLINK) {
+		return !(FORCE_HYPERLINK.length > 0 && parseInt(FORCE_HYPERLINK, 10) === 0);
 	}
 
 	if (hasFlag('no-hyperlink') || hasFlag('no-hyperlinks') || hasFlag('hyperlink=false') || hasFlag('hyperlink=never')) {
@@ -37,7 +53,7 @@ function supportsHyperlink(stream) {
 	}
 
 	// Netlify does not run a TTY, it does not need `supportsColor` check
-	if ('NETLIFY' in env) {
+	if (NETLIFY) {
 		return true;
 	}
 
@@ -54,18 +70,18 @@ function supportsHyperlink(stream) {
 		return false;
 	}
 
-	if ('CI' in env) {
+	if (CI) {
 		return false;
 	}
 
-	if ('TEAMCITY_VERSION' in env) {
+	if (TEAMCITY_VERSION) {
 		return false;
 	}
 
-	if ('TERM_PROGRAM' in env) {
-		const version = parseVersion(env.TERM_PROGRAM_VERSION);
+	if (TERM_PROGRAM) {
+		const version = parseVersion(TERM_PROGRAM_VERSION || '');
 
-		switch (env.TERM_PROGRAM) {
+		switch (TERM_PROGRAM) {
 			case 'iTerm.app':
 				if (version.major === 3) {
 					return version.minor >= 1;
@@ -80,13 +96,13 @@ function supportsHyperlink(stream) {
 		}
 	}
 
-	if ('VTE_VERSION' in env) {
+	if (VTE_VERSION) {
 		// 0.50.0 was supposed to support hyperlinks, but throws a segfault
-		if (env.VTE_VERSION === '0.50.0') {
+		if (VTE_VERSION === '0.50.0') {
 			return false;
 		}
 
-		const version = parseVersion(env.VTE_VERSION);
+		const version = parseVersion(VTE_VERSION);
 		return version.major > 0 || version.minor >= 50;
 	}
 
diff --git a/package.json b/package.json
index 40a45ff..76786c1 100644
--- a/package.json
+++ b/package.json
@@ -10,15 +10,16 @@
         "url": "github.com/jamestalmage"
     },
     "engines": {
-        "node": ">=8"
+        "node": ">=14.18"
     },
     "scripts": {
         "prepublishOnly": "npm run create-types",
-        "test": "xo && nyc ava",
-        "create-types": "tsc index.js --allowJs  --declaration --emitDeclarationOnly"
+        "test": "xo && nyc ava && tsc",
+        "create-types": "tsc --project declaration.tsconfig.json"
     },
     "files": [
         "index.js",
+        "index.d.ts",
         "browser.js"
     ],
     "browser": "browser.js",
@@ -33,10 +34,12 @@
         "supports-color": "^7.0.0"
     },
     "devDependencies": {
+        "@tsconfig/node14": "^1.0.3",
+        "@types/supports-color": "^8.1.1",
         "ava": "^2.2.0",
         "codecov": "^3.5.0",
         "nyc": "^14.1.1",
-        "typescript": "^3.7.2",
+        "typescript": "^4.9.5",
         "xo": "^0.24.0"
     },
     "nyc": {
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..1aa521a
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,12 @@
+{
+	"extends": "@tsconfig/node14/tsconfig.json",
+	"files": [
+		"index.js"
+	],
+	"compilerOptions": {
+		"allowJs": true,
+		"checkJs": true,
+		"noEmit": true,
+		"removeComments": true
+	}
+}