diff --git a/lib/web3.js b/lib/web3.js
index b240bda..9a85c4d 100644
--- a/lib/web3.js
+++ b/lib/web3.js
@@ -505,4 +505,5 @@ function messageHandler(data) {
     }
 }
 
-module.exports = web3;
+if (typeof(module) !== "undefined")
+    module.exports = web3;
diff --git a/lib/websocket.js b/lib/websocket.js
index ddb44ae..5b40075 100644
--- a/lib/websocket.js
+++ b/lib/websocket.js
@@ -74,4 +74,5 @@ Object.defineProperty(WebSocketProvider.prototype, "onmessage", {
     set: function(provider) { this.onMessage(provider); }
 });
 
-module.exports = WebSocketProvider;
+if (typeof(module) !== "undefined")
+    module.exports = WebSocketProvider;