diff --git a/js/lib/urlutil.js b/js/lib/urlutil.js
index ccd775e9c5a..3b6fd64a693 100644
--- a/js/lib/urlutil.js
+++ b/js/lib/urlutil.js
@@ -481,11 +481,12 @@ const UrlUtil = {
     // parsed.origin is specific to muon.url.parse
     if (parsed.origin !== undefined) {
       if (parsed.protocol === 'about:') {
-        return [parsed.protocol, parsed.path].join('')
+        return [parsed.protocol, parsed.path.replace(/\/.*/, '')].join('')
       }
       return parsed.origin.replace(/\/+$/, '')
     }
     if (parsed.host && parsed.protocol) {
+      // parsed.slashes is specific to node's url.parse
       return parsed.slashes ? [parsed.protocol, parsed.host].join('//') : [parsed.protocol, parsed.host].join('')
     }
     return null
diff --git a/test/unit/lib/urlutilTestComponents.js b/test/unit/lib/urlutilTestComponents.js
index dc797f708b9..55dd829f862 100644
--- a/test/unit/lib/urlutilTestComponents.js
+++ b/test/unit/lib/urlutilTestComponents.js
@@ -173,10 +173,10 @@ module.exports = {
 
   'isFileType': {
     'relative file': (test) => {
-      test.equal(urlUtil().isFileType('/file/abc/test.pdf', 'pdf'), true)
+      test.equal(urlUtil().isFileType('file:///file/abc/test.pdf', 'pdf'), true)
     },
     'relative path': (test) => {
-      test.equal(urlUtil().isFileType('/file/abc/test', 'pdf'), false)
+      test.equal(urlUtil().isFileType('file:///file/abc/test', 'pdf'), false)
     },
     'JPG URL': (test) => {
       test.equal(urlUtil().isFileType('http://example.com/test/ABC.JPG?a=b#test', 'jpg'), true)
@@ -365,7 +365,7 @@ module.exports = {
       test.strictEqual(urlUtil().getOrigin('https://abc.bing.com'), 'https://abc.bing.com')
     },
     'gets URL origin for url with port': (test) => {
-      test.strictEqual(urlUtil().getOrigin('https://bing.com:443/?test=1#abc'), 'https://bing.com:443')
+      test.strictEqual(urlUtil().getOrigin('https://bing.com:8000/?test=1#abc'), 'https://bing.com:8000')
     },
     'gets URL origin for IP host': (test) => {
       test.strictEqual(urlUtil().getOrigin('http://127.0.0.1:443/?test=1#abc'), 'http://127.0.0.1:443')
@@ -374,7 +374,11 @@ module.exports = {
       test.strictEqual(urlUtil().getOrigin('about:preferences#abc'), 'about:preferences')
     },
     'gets URL origin for slashless protocol URL': (test) => {
+      test.strictEqual(urlUtil().getOrigin('about:test'), 'about:test')
+      test.strictEqual(urlUtil().getOrigin('about:test/'), 'about:test')
       test.strictEqual(urlUtil().getOrigin('about:test/foo'), 'about:test')
+      test.strictEqual(urlUtil().getOrigin('about:test/foo/bar'), 'about:test')
+      test.strictEqual(urlUtil().getOrigin('about:test/foo/bar#baz'), 'about:test')
     },
     'returns null for invalid URL': (test) => {
       test.strictEqual(urlUtil().getOrigin('abc'), null)