diff --git a/README.md b/README.md
index e8f43e3b..c90e4019 100644
--- a/README.md
+++ b/README.md
@@ -409,7 +409,7 @@ openpgp.revokeKey(options).then(function(key) {
 #### Lookup public key on HKP server
 
 ```js
-var hkp = new openpgp.HKP('https://pgp.mit.edu');
+var hkp = new openpgp.HKP(); // Defaults to https://keyserver.ubuntu.com, or pass another keyserver URL as a string
 
 var options = {
     query: 'alice@example.com'
diff --git a/src/hkp.js b/src/hkp.js
index 37c5d7cb..a2b798a6 100644
--- a/src/hkp.js
+++ b/src/hkp.js
@@ -27,7 +27,8 @@ import config from './config';
  * Initialize the HKP client and configure it with the key server url and fetch function.
  * @constructor
  * @param {String}    keyServerBaseUrl  (optional) The HKP key server base url including
- *   the protocol to use e.g. https://pgp.mit.edu
+ *   the protocol to use, e.g. 'https://pgp.mit.edu'; defaults to
+ *   openpgp.config.keyserver (https://keyserver.ubuntu.com)
  */
 function HKP(keyServerBaseUrl) {
   this._baseUrl = keyServerBaseUrl || config.keyserver;
diff --git a/test/general/hkp.js b/test/general/hkp.js
index 0d5370d2..3906d2c9 100644
--- a/test/general/hkp.js
+++ b/test/general/hkp.js
@@ -105,6 +105,19 @@ describe('HKP unit tests', function() {
       '=5obP\r\n' +
       '-----END PGP PUBLIC KEY BLOCK-----';
 
+      const revocation_certificate = `-----BEGIN PGP PUBLIC KEY BLOCK-----
+      Comment: This is a revocation certificate
+
+      iQFFBCABCAAvFiEE6mWHlKTGvbGenE8BstiRuVIg7eYFAlxec9cRHQB0aGlzIGlz
+      IGEgdGVzdC4ACgkQstiRuVIg7eZkywf/QuHU6WaOGmI635xsV8GNyvOOHzDpVuzM
+      AYGIKOLf1l661aS1MIvbXGxI86a3CzLs3K9nqUS7uAZ89vhf6L8RDZSkpn2GzY3K
+      JQb0ZM+qf2TGkVDZ/wI8H/BMkJGCLbvbn6Ywk/o4GQIl/ISJPQTiC5VixayLEUQ3
+      6dnENegfEIptSOPNBOelRPfbT8tqcR6SxibjXYxlCqvdSgt7lui06vGcejl4qNgZ
+      oNMuvQNShV2G9KkPda3AZWCIWzUBuKN5UuE06u68iclH2ckEicQvnmxHnJU/BSC9
+      h3bdqlMa87hRGnWluKpJT+XRP0UGiN8UGWo8OEpdz8KbvVTCUVya4g==
+      =Wjv9
+      -----END PGP PUBLIC KEY BLOCK-----`
+
   beforeEach(function() {
     hkp = new openpgp.HKP(openpgp.config.keyserver);
   });
@@ -137,10 +150,16 @@ describe('HKP unit tests', function() {
     });
   });
 
-  describe('upload', function() {
+  describe('upload public key', function() {
     it('should work', function() {
       return hkp.upload(pub_key);
     });
   });
 
+  describe('upload revocation certificate', function() {
+    it('should work', function() {
+      return hkp.upload(revocation_certificate);
+    });
+  });
+
 });