--- a/index.js
+++ b/index.js
@@ -24,8 +24,8 @@
 /* eslint no-control-regex: 0 */
 class Header {
     constructor (options) {
-        this.headers = {};
-        this.headers_decoded = {};
+        this.headers = Object.create(null);
+        this.headers_decoded = Object.create(null);
         this.header_list = [];
         this.options = options;
     }
@@ -147,11 +147,13 @@
     }
 
     _add_header (key, value, method) {
+        if (key === "__proto__" || key === "constructor" || key === "prototype") return;
         this.headers[key] = this.headers[key] || [];
         this.headers[key][method](value);
     }
 
     _add_header_decode (key, value, method) {
+        if (key === "__proto__" || key === "constructor" || key === "prototype") return;
         const val = this.decode_header(value);
         // console.log(key + ': ' + val);
         this.headers_decoded[key] = this.headers_decoded[key] || [];