diff --git a/lib/freeze.js b/lib/freeze.js
index 4f7dd64..918d43e 100644
--- a/lib/freeze.js
+++ b/lib/freeze.js
@@ -32,12 +32,18 @@ function recur(object) {
  * Or if `process.env.UPDEEP_MODE === 'dangerously_never_freeze'`, this returns the original object
  * without freezing.
  *
+ * If in a browser and built without replacing process, never freeze.
+ *
  * @function
  * @sig a -> a
  * @param  {object} object Object to freeze.
  * @return {object} Frozen object, unless in production, then the same object.
  */
 function freeze(object) {
+  if (typeof process === 'undefined') {
+    return object
+  }
+
   if (process.env.NODE_ENV === 'production') {
     return object
   }