diff --git a/index.js b/index.js
index 7e9e294..da03db0 100644
--- a/index.js
+++ b/index.js
@@ -74,7 +74,7 @@ module.exports = (urlString, options) => {
 	if (urlObj.pathname) {
 		// TODO: Use the following instead when targeting Node.js 10
 		// `urlObj.pathname = urlObj.pathname.replace(/(?<!https?:)\/{2,}/g, '/');`
-		urlObj.pathname = urlObj.pathname.replace(/((?![https?:]).)\/{2,}/g, (_, p1) => {
+		urlObj.pathname = urlObj.pathname.replace(/((?!:).|^)\/{2,}/g, (_, p1) => {
 			if (/^(?!\/)/g.test(p1)) {
 				return `${p1}/`;
 			}
diff --git a/test.js b/test.js
index 9333d35..cb14874 100644
--- a/test.js
+++ b/test.js
@@ -31,6 +31,11 @@ test('main', t => {
 	t.is(normalizeUrl('http://sindresorhus.com////foo/bar'), 'http://sindresorhus.com/foo/bar');
 	t.is(normalizeUrl('http://sindresorhus.com////foo////bar'), 'http://sindresorhus.com/foo/bar');
 	t.is(normalizeUrl('//sindresorhus.com/', {normalizeProtocol: false}), '//sindresorhus.com');
+	t.is(normalizeUrl('//sindresorhus.com//foo', {normalizeProtocol: false}), '//sindresorhus.com/foo');
+	t.is(normalizeUrl('http://sindresorhus.com:5000///foo'), 'http://sindresorhus.com:5000/foo');
+	t.is(normalizeUrl('http://sindresorhus.com///foo'), 'http://sindresorhus.com/foo');
+	t.is(normalizeUrl('http://sindresorhus.com:5000//foo'), 'http://sindresorhus.com:5000/foo');
+	t.is(normalizeUrl('http://sindresorhus.com//foo'), 'http://sindresorhus.com/foo');
 	t.is(normalizeUrl('//sindresorhus.com:80/', {normalizeProtocol: false}), '//sindresorhus.com');
 	t.is(normalizeUrl('http://sindresorhus.com/foo#bar'), 'http://sindresorhus.com/foo#bar');
 	t.is(normalizeUrl('http://sindresorhus.com/foo#bar', {stripHash: true}), 'http://sindresorhus.com/foo');