diff --git a/build/index.js b/build/index.js
index 823154e..a306dd0 100644
--- a/build/index.js
+++ b/build/index.js
@@ -46,7 +46,7 @@ function jsonp(url, options) {
     }
 
     function serialize(params) {
-        var param = '?';
+        var param = '';
         for (var key in params) {
             if (params.hasOwnProperty(key)) {
                 param += '&' + key + '=' + encodeURIComponent(params[key]);
@@ -55,6 +55,14 @@ function jsonp(url, options) {
         return param;
     }
 
+    function handleUrl(url, params) {
+        if (!~url.indexOf('?')) {
+            url += '?';
+        }
+        url += serialize(params);
+        url = url.replace('?&', '?');
+    }
+
     promise = new Promise(function (resolve, reject) {
         if (timeout) {
             timer = setTimeout(function () {
@@ -67,8 +75,7 @@ function jsonp(url, options) {
             resolve(data);
         };
         params[callback] = id;
-        url += serialize(params);
-        url = url.replace('?&', '?');
+        url = handleUrl(url, params);
         // Create script.
         script = document.createElement('script');
         script.src = url;
diff --git a/package.json b/package.json
index b4a56c6..ae3b40c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "simple-jsonp-promise",
-  "version": "1.0.6",
+  "version": "1.0.7",
   "description": "",
   "main": "build/index.js",
   "scripts": {
diff --git a/src/index.js b/src/index.js
index 108e272..d1d00db 100644
--- a/src/index.js
+++ b/src/index.js
@@ -14,64 +14,71 @@ let count = 0;
  * - timeout {Number} how long after the request until a timeout error
  *   is emitted (defaults to `15000`)
  */
-function jsonp( url, options ) {
-    options      = options || {};
-    let prefix   = options.prefix || '__jp';
+function jsonp(url, options) {
+    options = options || {};
+    let prefix = options.prefix || '__jp';
     let callback = options.callback || 'callback';
-    let params   = options.data || {};
-    let timeout  = options.timeout ? options.timeout : 15000;
-    let target   = document.getElementsByTagName( 'script' )[ 0 ] || document.head;
+    let params = options.data || {};
+    let timeout = options.timeout ? options.timeout : 15000;
+    let target = document.getElementsByTagName('script')[0] || document.head;
     let script;
     let timer;
     let promise;
     // Generate a unique id for the request.
-    let id       = prefix + (count++);
+    let id = prefix + (count++);
 
     function noop() {}
 
     function cleanup() {
         // Remove the script tag.
-        if ( script && script.parentNode ) {
-            script.parentNode.removeChild( script );
+        if (script && script.parentNode) {
+            script.parentNode.removeChild(script);
+        }
+        window[id] = noop;
+        if (timer) {
+            clearTimeout(timer);
         }
-        window[ id ] = noop;
-        if ( timer ) { clearTimeout( timer ); }
     }
 
-    function serialize( params ) {
-        let param = '?';
-        for ( let key in params ) {
-            if ( params.hasOwnProperty( key ) ) {
+    function serialize(params) {
+        let param = '';
+        for (let key in params) {
+            if (params.hasOwnProperty(key)) {
                 param += `&${key}=${encodeURIComponent( params[ key ] )}`;
             }
         }
         return param;
     }
 
-    promise = new Promise( ( resolve, reject ) => {
-        if ( timeout ) {
-            timer = setTimeout( () => {
+    function handleUrl(url, params) {
+        if (!~url.indexOf('?')) { url += '?'; }
+        url += serialize(params);
+        url = url.replace('?&', '?');
+    }
+
+    promise = new Promise((resolve, reject) => {
+        if (timeout) {
+            timer = setTimeout(() => {
                 cleanup();
-                reject( new Error( 'Timeout' ) );
-            }, timeout );
+                reject(new Error('Timeout'));
+            }, timeout);
         }
-        window[ id ]       = function( data ) {
+        window[id] = function (data) {
             cleanup();
-            resolve( data );
+            resolve(data);
         };
-        params[ callback ] = id;
-        url += serialize( params );
-        url                = url.replace( '?&', '?' );
+        params[callback] = id;
+        url = handleUrl(url, params);
         // Create script.
-        script             = document.createElement( 'script' );
-        script.src         = url;
-        script.onerror     = function() {
+        script = document.createElement('script');
+        script.src = url;
+        script.onerror = function () {
             cleanup();
-            reject( new Error( 'Network Error' ) );
+            reject(new Error('Network Error'));
         };
-        target.parentNode.insertBefore( script, target );
-    } );
+        target.parentNode.insertBefore(script, target);
+    });
     return promise;
 }
 
-export default jsonp;
+export default jsonp;
\ No newline at end of file