diff --git a/.gitignore b/.gitignore
index 368fbf5..2518a0b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ node_modules
 npm-debug.log
 .DS_Store
 /polyfill/index.js
+coverage
diff --git a/src/index.mjs b/src/index.mjs
index 96066f6..84c7f43 100644
--- a/src/index.mjs
+++ b/src/index.mjs
@@ -1,37 +1,22 @@
+import response from './lib/response';
+
+const regex = /^(.*?):[^\S\n]*([\s\S]*?)$/gm;
+
 export default function(url, options) {
 	options = options || {};
 	return new Promise( (resolve, reject) => {
 		const request = new XMLHttpRequest();
-		const keys = [];
-		const all = [];
-		const headers = {};
-
-		const response = () => ({
-			ok: (request.status/100|0) == 2,		// 200-299
-			statusText: request.statusText,
-			status: request.status,
-			url: request.responseURL,
-			text: () => Promise.resolve(request.responseText),
-			json: () => Promise.resolve(request.responseText).then(JSON.parse),
-			blob: () => Promise.resolve(new Blob([request.response])),
-			clone: response,
-			headers: {
-				keys: () => keys,
-				entries: () => all,
-				get: n => headers[n.toLowerCase()],
-				has: n => n.toLowerCase() in headers
-			}
-		});
 
 		request.open(options.method || 'get', url, true);
 
 		request.onload = () => {
-			request.getAllResponseHeaders().replace(/^(.*?):[^\S\n]*([\s\S]*?)$/gm, (m, key, value) => {
-				keys.push(key = key.toLowerCase());
+			const all = [], keys = [], raw = {};
+			request.getAllResponseHeaders().replace(regex, (m, key, value) => {
 				all.push([key, value]);
-				headers[key] = headers[key] ? `${headers[key]},${value}` : value;
+				keys.push(key = key.toLowerCase());
+				raw[key] = raw[key] ? `${raw[key]},${value}` : value;
 			});
-			resolve(response());
+			resolve(response(request, all, keys, raw));
 		};
 
 		request.onerror = reject;
diff --git a/src/lib/response.mjs b/src/lib/response.mjs
new file mode 100644
index 0000000..4c2a548
--- /dev/null
+++ b/src/lib/response.mjs
@@ -0,0 +1,18 @@
+export default function response (request, all, keys, raw) {
+	return {
+		ok: (request.status/100|0) == 2,		// 200-299
+		statusText: request.statusText,
+		status: request.status,
+		url: request.responseURL,
+		text: () => Promise.resolve(request.responseText),
+		json: () => Promise.resolve(request.responseText).then(JSON.parse),
+		blob: () => Promise.resolve(new Blob([request.response])),
+		clone: () => response(request, all, keys, raw),
+		headers: {
+			keys: () => keys,
+			entries: () => all,
+			get: n => raw[n.toLowerCase()],
+			has: n => n.toLowerCase() in raw
+		}
+	};
+}
diff --git a/test/lib/response.js b/test/lib/response.js
new file mode 100644
index 0000000..24cd324
--- /dev/null
+++ b/test/lib/response.js
@@ -0,0 +1,32 @@
+import response from '../../src/lib/response.mjs';
+
+describe('response()', () => {
+	const raw = { 'x-foo': 'foo', 'x-bar': 'bar' };
+	const keys = Object.keys(raw);
+	const all = Object.entries(raw);
+	const resp = response({}, all, keys, raw);
+
+	it('returns text()', () => response({ responseText: 'A passing test.' }, [], [], {})
+		.text()
+		.then((text) => expect(text).toBe('A passing test.'))
+	);
+
+	it('returns blob()', () => response({ response: 'A passing test.' })
+		.blob()
+		.then((text) => expect(text.toString()).toBe(new Blob(['A passing test.']).toString()))
+	);
+
+	it('returns headers', () => {
+		expect(resp.headers.entries()).toEqual(all);
+	});
+
+	it('returns header keys', () => {
+		expect(resp.headers.keys()).toEqual(['x-foo', 'x-bar']);
+	});
+
+	it('returns headers has', () => {
+		expect(resp.headers.has('x-foo')).toBe(true);
+		expect(resp.headers.has('x-bar')).toBe(true);
+		expect(resp.headers.has('x-baz')).toBe(false);
+	});
+});