diff --git a/lib/url.js b/lib/url.js
index 6562be5d8302e6..80d0824fbe72ea 100644
--- a/lib/url.js
+++ b/lib/url.js
@@ -217,13 +217,13 @@ Url.prototype.parse = function parse(url, parseQueryString, slashesDenoteHost) {
   if (slashesDenoteHost || proto || hostPattern.test(rest)) {
     var slashes = rest.charCodeAt(0) === 47/*/*/ &&
                   rest.charCodeAt(1) === 47/*/*/;
-    if (slashes && !(proto && hostlessProtocol[proto])) {
+    if (slashes && !(proto && hostlessProtocol[lowerProto])) {
       rest = rest.slice(2);
       this.slashes = true;
     }
   }
 
-  if (!hostlessProtocol[proto] &&
+  if (!hostlessProtocol[lowerProto] &&
       (slashes || (proto && !slashedProtocol[proto]))) {
 
     // there's a hostname.
diff --git a/test/parallel/test-url-parse-format.js b/test/parallel/test-url-parse-format.js
index 0e12fe52516f16..c8daf90c159508 100644
--- a/test/parallel/test-url-parse-format.js
+++ b/test/parallel/test-url-parse-format.js
@@ -890,6 +890,39 @@ const parseTests = {
     pathname: '/*',
     path: '/*',
     href: 'https:///*'
+  },
+
+  // The following two URLs are the same, but they differ for
+  // a capital A: it is important that we verify that the protocol
+  // is checked in a case-insensitive manner.
+  'javascript:alert(1);a=\x27@white-listed.com\x27': {
+    protocol: 'javascript:',
+    slashes: null,
+    auth: null,
+    host: null,
+    port: null,
+    hostname: null,
+    hash: null,
+    search: null,
+    query: null,
+    pathname: "alert(1);a='@white-listed.com'",
+    path: "alert(1);a='@white-listed.com'",
+    href: "javascript:alert(1);a='@white-listed.com'"
+  },
+
+  'javAscript:alert(1);a=\x27@white-listed.com\x27': {
+    protocol: 'javascript:',
+    slashes: null,
+    auth: null,
+    host: null,
+    port: null,
+    hostname: null,
+    hash: null,
+    search: null,
+    query: null,
+    pathname: "alert(1);a='@white-listed.com'",
+    path: "alert(1);a='@white-listed.com'",
+    href: "javascript:alert(1);a='@white-listed.com'"
   }
 };
 
@@ -921,3 +954,25 @@ for (const u in parseTests) {
   assert.strictEqual(actual, expected,
                      `format(${u}) == ${u}\nactual:${actual}`);
 }
+
+{
+  const parsed = url.parse('http://nodejs.org/')
+    .resolveObject('jAvascript:alert(1);a=\x27@white-listed.com\x27');
+
+  const expected = Object.assign(new url.Url(), {
+    protocol: 'javascript:',
+    slashes: null,
+    auth: null,
+    host: null,
+    port: null,
+    hostname: null,
+    hash: null,
+    search: null,
+    query: null,
+    pathname: "alert(1);a='@white-listed.com'",
+    path: "alert(1);a='@white-listed.com'",
+    href: "javascript:alert(1);a='@white-listed.com'"
+  });
+
+  assert.deepStrictEqual(parsed, expected);
+}