diff --git a/README.md b/README.md
index 43b6bb8..031a1cb 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,7 @@ git clone https://github.com/ading2210/libcurl.js
 cd libcurl.js/client
 ./build.sh
 ```
-Make sure you have emscripten, git, and the various C build tools installed. The build script will generate `client/out/libcurl.js`.
+Make sure you have emscripten, git, and the various C build tools installed. The build script will generate `client/out/libcurl.js` as well as `client/out/libcurl_module.mjs`, which is an ES6 module.
 
 ## Javascript API:
 
@@ -41,6 +41,12 @@ let r = await libcurl.fetch("https://ading.dev");
 console.log(await r.text());
 ```
 
+### Changing the Websocket URL:
+You can change the URL of the websocket proxy by using `libcurl.set_websocket`.
+```js
+libcurl.set_websocket("ws://localhost:6001/");
+```
+
 ## Proxy Server:
 The proxy server consists of a [SOCKS5 proxy server](https://github.com/Amaindex/asyncio-socks-server) behind a [websocket TCP proxy](https://github.com/novnc/websockify). 
 
diff --git a/client/build.sh b/client/build.sh
index a894253..57dfd04 100755
--- a/client/build.sh
+++ b/client/build.sh
@@ -5,7 +5,8 @@ set -e
 INCLUDE_DIR="build/curl-wasm/include/"
 LIB_DIR="build/curl-wasm/lib/"
 OUT_FILE="out/libcurl.js"
-MODULE_FILE="out/libcurl_module.js"
+ES6_FILE="out/libcurl_module.mjs"
+MODULE_FILE="out/emscripten_compiled.js"
 WRAPPER_SOURCE="main.js"
 
 EXPORTED_FUNCS="_load_certs,_perform_request"
@@ -13,6 +14,10 @@ RUNTIME_METHODS="addFunction,removeFunction,allocate,ALLOC_NORMAL"
 COMPILER_OPTIONS="-o $MODULE_FILE -lcurl -lssl -lcrypto -lcjson -lz -lbrotlidec -lbrotlicommon -I $INCLUDE_DIR -L $LIB_DIR"
 EMSCRIPTEN_OPTIONS="-lwebsocket.js -sSINGLE_FILE -sASYNCIFY -sALLOW_TABLE_GROWTH -sEXPORTED_FUNCTIONS=$EXPORTED_FUNCS -sEXPORTED_RUNTIME_METHODS=$RUNTIME_METHODS"
 
+if [ "$1" = "release" ]; then
+  COMPILER_OPTIONS="-O3 $COMPILER_OPTIONS"
+fi
+
 #ensure deps are compiled
 tools/all_deps.sh
 tools/generate_cert.sh
@@ -32,4 +37,9 @@ sed -i 's/function _emscripten_console_error(str) {/& if(UTF8ToString(str).endsW
 
 #merge compiled emscripten module and wrapper code
 cp $WRAPPER_SOURCE $OUT_FILE
-sed -i "/__emscripten_output__/r $MODULE_FILE" $OUT_FILE
\ No newline at end of file
+sed -i "/__emscripten_output__/r $MODULE_FILE" $OUT_FILE
+rm $MODULE_FILE
+
+#generate es6 module
+cp $OUT_FILE $ES6_FILE
+sed -i 's/window.libcurl/export const libcurl/' $ES6_FILE
\ No newline at end of file
diff --git a/client/main.c b/client/main.c
index c7e1036..9e7f7fc 100644
--- a/client/main.c
+++ b/client/main.c
@@ -103,6 +103,7 @@ void perform_request(const char* url, const char* json_params, DataCallback data
   curl_multi_add_handle(multi_handle, http_handle);
   
   CURLMcode mc;
+  struct CURLMsg *m;
   do {
     mc = curl_multi_perform(multi_handle, &still_running);
  
@@ -114,12 +115,15 @@ void perform_request(const char* url, const char* json_params, DataCallback data
       break;
     }
 
+    int msgq = 0;
+    m = curl_multi_info_read(multi_handle, &msgq);
+
     //ensure we dont block the main thread
     emscripten_sleep(0);
  
   } while(still_running);
   
-  int error = (int) mc;
+  int error = (int) m->data.result;
   long response_code;
   curl_easy_getinfo(http_handle, CURLINFO_RESPONSE_CODE, &response_code);
 
diff --git a/client/main.js b/client/main.js
index b55c29c..d8ff917 100644
--- a/client/main.js
+++ b/client/main.js
@@ -96,6 +96,7 @@ class Headers {
       }
     }
     this[prop] = value;
+    return true;
   }
 }
 
@@ -214,6 +215,7 @@ function libcurl_fetch(url, params={}) {
     let finish_callback = (error, response_info) => {
       if (error != 0) {
         reject("libcurl.js encountered an error: " + error);
+        return;
       }
       let response_data = merge_arrays(chunks);
       let response_obj = create_response(response_data, response_info);