diff --git a/package.json b/package.json
index f150ca0..b4a56c6 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "simple-jsonp-promise",
-  "version": "1.0.5",
+  "version": "1.0.6",
   "description": "",
   "main": "build/index.js",
   "scripts": {
diff --git a/src/index.js b/src/index.js
index 53410f8..108e272 100644
--- a/src/index.js
+++ b/src/index.js
@@ -39,7 +39,7 @@ function jsonp( url, options ) {
     }
 
     function serialize( params ) {
-        let param = '';
+        let param = '?';
         for ( let key in params ) {
             if ( params.hasOwnProperty( key ) ) {
                 param += `&${key}=${encodeURIComponent( params[ key ] )}`;