diff --git a/ghost/core/core/frontend/helpers/url.js b/ghost/core/core/frontend/helpers/url.js
index df62bd954b..c99213f4a0 100644
--- a/ghost/core/core/frontend/helpers/url.js
+++ b/ghost/core/core/frontend/helpers/url.js
@@ -17,7 +17,7 @@ module.exports = function url(options) {
     let outputUrl = getMetaDataUrl(this, absolute);
 
     try {
-        outputUrl = encodeURI(decodeURI(outputUrl));
+        outputUrl = encodeURI(decodeURI(outputUrl)).replace(/%5B/g, '[').replace(/%5D/g, ']');
     } catch (err) {
         // Happens when the outputURL contains an invalid URI character like "%%" or "%80"
 
diff --git a/ghost/core/test/unit/frontend/helpers/url.test.js b/ghost/core/test/unit/frontend/helpers/url.test.js
index e17700f531..97cf8d505d 100644
--- a/ghost/core/test/unit/frontend/helpers/url.test.js
+++ b/ghost/core/test/unit/frontend/helpers/url.test.js
@@ -225,6 +225,14 @@ describe('{{url}} helper', function () {
             should.exist(rendered);
             rendered.string.should.equal('');
         });
+
+        it('should not encode square brackets (as in valid IPV6 addresses)', function () {
+            rendered = url.call(
+                {url: 'http://[ffff::]:2368/baz', label: 'Baz', slug: 'baz', current: true},
+                {hash: {absolute: 'true'}});
+            should.exist(rendered);
+            rendered.string.should.equal('http://[ffff::]:2368/baz');
+        });
     });
 
     describe('with subdir', function () {