diff --git a/markdown-it-attrs.browser.js b/markdown-it-attrs.browser.js
index 1078e26..7437725 100644
--- a/markdown-it-attrs.browser.js
+++ b/markdown-it-attrs.browser.js
@@ -11,11 +11,9 @@ var defaultOptions = {
   allowedAttributes: []
 };
 
-module.exports = function attributes(md, options) {
-  if (!options) {
-    options = defaultOptions;
-  }
-
+module.exports = function attributes(md, options_) {
+  var options = Object.assign({}, defaultOptions);
+  options = Object.assign(options, options_);
   var patterns = patternsConfig(options);
 
   function curlyAttrs(state) {
diff --git a/package-lock.json b/package-lock.json
index 4cdf875..43f7516 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "markdown-it-attrs",
-  "version": "2.4.0",
+  "version": "2.4.1",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index bf4d3df..e5c7263 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "markdown-it-attrs",
-  "version": "2.4.0",
+  "version": "2.4.1",
   "description": "Add classes, identifiers and attributes to your markdown with {} curly brackets, similar to pandoc's header attributes",
   "main": "index.js",
   "license": "MIT",