diff --git a/browser.js b/browser.js
index b339dca..6e6c20c 100644
--- a/browser.js
+++ b/browser.js
@@ -8,20 +8,14 @@ const MAX_BYTES = 65536
 // https://github.com/nodejs/node/blob/master/lib/internal/crypto/random.js#L48
 const MAX_UINT32 = 4294967295
 
-function oldBrowser () {
-  throw new Error('Secure random number generation is not supported by this browser.\nUse Chrome, Firefox or Internet Explorer 11')
-}
-
-const _global = typeof globalThis !== 'undefined' ? globalThis : global
-const crypto = _global.crypto || _global.msCrypto
+export function randomBytes (size, cb) {
+  const _global = typeof globalThis !== 'undefined' ? globalThis : global
+  const crypto = _global.crypto || _global.msCrypto
 
-if (crypto && crypto.getRandomValues) {
-  module.exports = randomBytes
-} else {
-  module.exports = oldBrowser
-}
+  if (!crypto || !crypto.getRandomValues) {
+    throw new Error('Secure random number generation is not supported by this browser.\nUse Chrome, Firefox or Internet Explorer 11')
+  }
 
-function randomBytes (size, cb) {
   // phantomjs needs to throw
   if (size > MAX_UINT32) throw new RangeError('requested too many random bytes')
 
@@ -47,4 +41,4 @@ function randomBytes (size, cb) {
   }
 
   return bytes
-}
\ No newline at end of file
+}
diff --git a/package.json b/package.json
index 2627501..9a639e6 100644
--- a/package.json
+++ b/package.json
@@ -28,5 +28,6 @@
     "tap-spec": "^5.0.0",
     "tape": "^5.2.2",
     "zuul": "^3.12.0"
-  }
+  },
+  "sideEffects": false
 }