diff --git a/lib/sse.js b/lib/sse.js
index d9a0873..e6e7f56 100644
--- a/lib/sse.js
+++ b/lib/sse.js
@@ -40,8 +40,9 @@ var SSE = function (url, options) {
   /** @type { {[key: string]: EventListener} } */
   this.listeners = {};
 
-
+  /** @type {XMLHttpRequest} */
   this.xhr = null;
+  /** @type {number} */
   this.readyState = this.INITIALIZING;
   /** @type {number} */
   this.progress = 0;
@@ -285,11 +286,11 @@ if (typeof exports !== 'undefined') {
 export { SSE };
 
 /**
- * @typedef { {[key: string]: string} } SSEHeader
+ * @typedef { {[key: string]: string} } SSEHeaders
  */
 /**
  * @typedef {Object} SSEOptions
- * @property {SSEHeader} headers - headers
+ * @property {SSEHeaders} headers - headers
  * @property {string} payload - payload as a string
  * @property {string} method - HTTP Method
  * @property {boolean} withCredentials - flag, if credentials needed