diff --git a/src/EventSource.js b/src/EventSource.js
index 6a7b146..cbc46b5 100644
--- a/src/EventSource.js
+++ b/src/EventSource.js
@@ -31,12 +31,22 @@ class EventSource {
     this.timeout = options.timeout ?? 0;
     this.timeoutBeforeConnection = options.timeoutBeforeConnection ?? 500;
     this.withCredentials = options.withCredentials || false;
-    this.headers = options.headers || {};
     this.body = options.body || undefined;
     this.debug = options.debug || false;
     this.interval = options.pollingInterval ?? 5000;
     this.lineEndingCharacter = options.lineEndingCharacter || null;
 
+    const defaultHeaders = {
+      Accept: 'text/event-stream',
+      'Cache-Control': 'no-cache',
+      'X-Requested-With': 'XMLHttpRequest',
+    };
+
+    this.headers = {
+      ...defaultHeaders,
+     ...options.headers
+    };
+
     this._xhr = null;
     this._pollTimer = null;
     this._lastIndexProcessed = 0;
@@ -76,14 +86,8 @@ class EventSource {
         this._xhr.withCredentials = true;
       }
 
-      this._xhr.setRequestHeader('Accept', 'text/event-stream');
-      this._xhr.setRequestHeader('Cache-Control', 'no-cache');
-      this._xhr.setRequestHeader('X-Requested-With', 'XMLHttpRequest');
-
-      if (this.headers) {
-        for (const [key, value] of Object.entries(this.headers)) {
-          this._xhr.setRequestHeader(key, value);
-        }
+      for (const [key, value] of Object.entries(this.headers)) {
+        if(value) this._xhr.setRequestHeader(key, value);
       }
 
       if (this.lastEventId !== null) {
@@ -196,6 +200,7 @@ class EventSource {
     }
 
     const parts = response.substring(this._lastIndexProcessed, indexOfDoubleNewline).split(this.lineEndingCharacter);
+
     this._lastIndexProcessed = indexOfDoubleNewline;
 
     let type = undefined;