diff --git a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js
index eece232ac0..8f53cf0157 100644
--- a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js
+++ b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js
@@ -383,12 +383,16 @@
 
     _computeDiffURL: function(changeNum, patchRange, path) {
       // @see Issue 4255 regarding double-encoding.
+      path = encodeURIComponent(encodeURIComponent(path));
+      // @see Issue 4577 regarding more readable URLs.
+      path = path.replace(/%252F/g, '/');
+      path = path.replace(/%2520/g, '+');
       return '/c/' +
           encodeURIComponent(changeNum) +
           '/' +
           encodeURIComponent(this._patchRangeStr(patchRange)) +
           '/' +
-          encodeURIComponent(encodeURIComponent(path));
+          path;
     },
 
     _patchRangeStr: function(patchRange) {
diff --git a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.html b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.html
index 3fe785e5b2..76aceef586 100644
--- a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.html
+++ b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.html
@@ -39,6 +39,7 @@ limitations under the License.
     setup(function() {
       stub('gr-rest-api-interface', {
         getLoggedIn: function() { return Promise.resolve(true); },
+        getPreferences: function() { return Promise.resolve({}); },
       });
       element = fixture('basic');
     });
@@ -312,9 +313,9 @@ limitations under the License.
       diffStub.restore();
     });
 
-    test('file name should be double-escaped', function() {
+    test('path should be properly escaped', function() {
       element._files = [
-        {__path: 'my+file.txt'},
+        {__path: 'foo bar/my+file.txt%'},
       ];
       element.changeNum = '42';
       element.patchRange = {
@@ -322,8 +323,12 @@ limitations under the License.
         patchNum: '2',
       };
       flushAsynchronousOperations();
+      // Slashes should be preserved, and spaces should be translated to `+`.
+      // @see Issue 4255 regarding double-encoding.
+      // @see Issue 4577 regarding more readable URLs.
       assert.equal(
-          element.$$('a').getAttribute('href'), '/c/42/2/my%252Bfile.txt');
+          element.$$('a').getAttribute('href'),
+          '/c/42/2/foo+bar/my%252Bfile.txt%2525');
     });
   });
 </script>
diff --git a/polygerrit-ui/app/elements/core/gr-router/gr-router.js b/polygerrit-ui/app/elements/core/gr-router/gr-router.js
index 1ddff39c9d..a182f8a45b 100644
--- a/polygerrit-ui/app/elements/core/gr-router/gr-router.js
+++ b/polygerrit-ui/app/elements/core/gr-router/gr-router.js
@@ -135,12 +135,17 @@
       // Don't allow diffing the same patch number against itself.
       if (params.basePatchNum === params.patchNum) {
         // @see Issue 4255 regarding double-encoding.
+        var path = encodeURIComponent(encodeURIComponent(path));
+        // @see Issue 4577 regarding more readable URLs.
+        path = path.replace(/%252F/g, '/');
+        path = path.replace(/%2520/g, '+');
+
         page.redirect('/c/' +
             encodeURIComponent(params.changeNum) +
             '/' +
             encodeURIComponent(params.patchNum) +
             '/' +
-            encodeURIComponent(encodeURIComponent(params.path)));
+            path);
         return;
       }