diff --git a/CHANGELOG.md b/CHANGELOG.md
index 017c2b3b..37b1d3f0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## **6.11.0
+- [New] [Fix] `stringify`: revert 0e903c0; add `commaRoundTrip` option (#442)
+- [readme] fix version badge
+
 ## **6.10.5**
 - [Fix] `stringify`: with `arrayFormat: comma`, properly include an explicit `[]` on a single-item array (#434)
 
diff --git a/dist/qs.js b/dist/qs.js
index 94baf8ff..1c620a48 100644
--- a/dist/qs.js
+++ b/dist/qs.js
@@ -366,6 +366,7 @@ var stringify = function stringify(
     object,
     prefix,
     generateArrayPrefix,
+    commaRoundTrip,
     strictNullHandling,
     skipNulls,
     encoder,
@@ -430,7 +431,7 @@ var stringify = function stringify(
                 for (var i = 0; i < valuesArray.length; ++i) {
                     valuesJoined += (i === 0 ? '' : ',') + formatter(encoder(valuesArray[i], defaults.encoder, charset, 'value', format));
                 }
-                return [formatter(keyValue) + '=' + valuesJoined];
+                return [formatter(keyValue) + (commaRoundTrip && isArray(obj) && valuesArray.length === 1 ? '[]' : '') + '=' + valuesJoined];
             }
             return [formatter(keyValue) + '=' + formatter(encoder(obj, defaults.encoder, charset, 'value', format))];
         }
@@ -454,6 +455,8 @@ var stringify = function stringify(
         objKeys = sort ? keys.sort(sort) : keys;
     }
 
+    var adjustedPrefix = commaRoundTrip && isArray(obj) && obj.length === 1 ? prefix + '[]' : prefix;
+
     for (var j = 0; j < objKeys.length; ++j) {
         var key = objKeys[j];
         var value = typeof key === 'object' && typeof key.value !== 'undefined' ? key.value : obj[key];
@@ -463,8 +466,8 @@ var stringify = function stringify(
         }
 
         var keyPrefix = isArray(obj)
-            ? typeof generateArrayPrefix === 'function' ? generateArrayPrefix(prefix, key) : prefix
-            : prefix + (allowDots ? '.' + key : '[' + key + ']');
+            ? typeof generateArrayPrefix === 'function' ? generateArrayPrefix(adjustedPrefix, key) : adjustedPrefix
+            : adjustedPrefix + (allowDots ? '.' + key : '[' + key + ']');
 
         sideChannel.set(object, step);
         var valueSideChannel = getSideChannel();
@@ -473,6 +476,7 @@ var stringify = function stringify(
             value,
             keyPrefix,
             generateArrayPrefix,
+            commaRoundTrip,
             strictNullHandling,
             skipNulls,
             encoder,
@@ -569,6 +573,10 @@ module.exports = function (object, opts) {
     }
 
     var generateArrayPrefix = arrayPrefixGenerators[arrayFormat];
+    if (opts && 'commaRoundTrip' in opts && typeof opts.commaRoundTrip !== 'boolean') {
+        throw new TypeError('`commaRoundTrip` must be a boolean, or absent');
+    }
+    var commaRoundTrip = generateArrayPrefix === 'comma' && opts && opts.commaRoundTrip;
 
     if (!objKeys) {
         objKeys = Object.keys(obj);
@@ -589,6 +597,7 @@ module.exports = function (object, opts) {
             obj[key],
             key,
             generateArrayPrefix,
+            commaRoundTrip,
             options.strictNullHandling,
             options.skipNulls,
             options.encode ? options.encoder : null,
@@ -1469,8 +1478,9 @@ function addNumericSeparator(num, str) {
     return $replace.call(str, sepRegex, '$&_');
 }
 
-var inspectCustom = require('./util.inspect').custom;
-var inspectSymbol = inspectCustom && isSymbol(inspectCustom) ? inspectCustom : null;
+var utilInspect = require('./util.inspect');
+var inspectCustom = utilInspect.custom;
+var inspectSymbol = isSymbol(inspectCustom) ? inspectCustom : null;
 
 module.exports = function inspect_(obj, options, depth, seen) {
     var opts = options || {};
@@ -1560,7 +1570,7 @@ module.exports = function inspect_(obj, options, depth, seen) {
         return inspect_(value, opts, depth + 1, seen);
     }
 
-    if (typeof obj === 'function') {
+    if (typeof obj === 'function' && !isRegExp(obj)) { // in older engines, regexes are callable
         var name = nameOf(obj);
         var keys = arrObjKeys(obj, inspect);
         return '[Function' + (name ? ': ' + name : ' (anonymous)') + ']' + (keys.length > 0 ? ' { ' + $join.call(keys, ', ') + ' }' : '');
@@ -1590,15 +1600,15 @@ module.exports = function inspect_(obj, options, depth, seen) {
     }
     if (isError(obj)) {
         var parts = arrObjKeys(obj, inspect);
-        if ('cause' in obj && !isEnumerable.call(obj, 'cause')) {
+        if (!('cause' in Error.prototype) && 'cause' in obj && !isEnumerable.call(obj, 'cause')) {
             return '{ [' + String(obj) + '] ' + $join.call($concat.call('[cause]: ' + inspect(obj.cause), parts), ', ') + ' }';
         }
         if (parts.length === 0) { return '[' + String(obj) + ']'; }
         return '{ [' + String(obj) + '] ' + $join.call(parts, ', ') + ' }';
     }
     if (typeof obj === 'object' && customInspect) {
-        if (inspectSymbol && typeof obj[inspectSymbol] === 'function') {
-            return obj[inspectSymbol]();
+        if (inspectSymbol && typeof obj[inspectSymbol] === 'function' && utilInspect) {
+            return utilInspect(obj, { depth: maxDepth - depth });
         } else if (customInspect !== 'symbol' && typeof obj.inspect === 'function') {
             return obj.inspect();
         }
diff --git a/package.json b/package.json
index d07ebd9b..2ff42f37 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
     "name": "qs",
     "description": "A querystring parser that supports nesting and arrays, with a depth limit",
     "homepage": "https://github.com/ljharb/qs",
-    "version": "6.10.5",
+    "version": "6.11.0",
     "repository": {
         "type": "git",
         "url": "https://github.com/ljharb/qs.git"