diff --git a/src/superagent.js b/src/superagent.js
index 1f66ea11a..446077902 100644
--- a/src/superagent.js
+++ b/src/superagent.js
@@ -144,7 +144,7 @@ class Request {
         if (!(this.fetchOptions.body instanceof FormData)) this.fetchOptions.body = new FormData();
         const data = fs.readFileSync(filepath, 'utf8');
         this.fetchOptions.body.append(name, new Blob([data]), path.basename(filepath));
-        this.fetchOptions.headers.set('Content-Type', 'multipart/form-data');
+        this.fetchOptions.headers.delete('Content-Type'); // explicitly remove it. without it boundary won't make it to the header!
         return this;
     }
 
diff --git a/src/test/superagent-test.js b/src/test/superagent-test.js
index ac79ce5be..6d08876ff 100644
--- a/src/test/superagent-test.js
+++ b/src/test/superagent-test.js
@@ -1,6 +1,5 @@
 /* global it:false */
 /* global describe:false */
-/* global before:false */
 
 'use strict';
 
@@ -22,4 +21,8 @@ describe('Superagent', function () {
         const [error] = await safe(superagent.get('https://cloudron.io').set('User-Agent', 'Mozilla').timeout(10*1000).redirects(0));
         expect(error).to.be.ok();
     });
+
+    it('can disable certs', async function () {
+        await superagent.get('https://www.cloudron.io').set('User-Agent', 'Mozilla').disableTLSCerts();
+    });
 });