diff --git a/index.js b/index.js
index 843da72..060ce5f 100644
--- a/index.js
+++ b/index.js
@@ -9,6 +9,7 @@ var isFn = function (fn) {
 }
 
 var isFS = function (stream) {
+  if (!fs) return false // browser
   return (stream instanceof (fs.ReadStream || noop) || stream instanceof (fs.WriteStream || noop)) && isFn(stream.close)
 }
 
diff --git a/package.json b/package.json
index 6781698..69b8e09 100644
--- a/package.json
+++ b/package.json
@@ -4,6 +4,9 @@
   "repository": "git://github.com/mafintosh/pump.git",
   "license": "MIT",
   "description": "pipe streams together and close all of them if one of them closes",
+  "browser": {
+    "fs": false
+  },
   "keywords": [
     "streams",
     "pipe",