diff --git a/cfg/conf.ini.sample b/cfg/conf.ini.sample
index 60c25871..8e1204f9 100644
--- a/cfg/conf.ini.sample
+++ b/cfg/conf.ini.sample
@@ -53,6 +53,12 @@ languageselection = false
 ; the pastes encryption key
 ; urlshortener = "https://shortener.example.com/api?link="
 
+; (optional) vizhash is a weak mechanism to detect if a comment was from a
+; different user when the same username was used in a comment. It is based on
+; the IP and might be used to get the posters IP if the server salt is leaked
+; and a rainbow table is generated for all IPs. Enabled by default.
+; vizhash = false
+
 ; stay compatible with PrivateBin Alpha 0.19, less secure
 ; if enabled will use base64.js version 1.7 instead of 2.1.9 and sha1 instead of
 ; sha256 in HMAC for the deletion token
diff --git a/lib/configuration.php b/lib/configuration.php
index 18a6a401..c99ddda3 100644
--- a/lib/configuration.php
+++ b/lib/configuration.php
@@ -44,6 +44,7 @@ class configuration
             'languageselection' => false,
             'languagedefault' => '',
             'urlshortener' => '',
+            'vizhash' => true,
             'zerobincompatibility' => false,
         ),
         'expire' => array(
diff --git a/lib/model/comment.php b/lib/model/comment.php
index 1d180bfc..9393b016 100644
--- a/lib/model/comment.php
+++ b/lib/model/comment.php
@@ -174,16 +174,19 @@ class model_comment extends model_abstract
         if (!sjcl::isValid($nickname)) throw new Exception('Invalid data.', 66);
         $this->_data->meta->nickname = $nickname;
 
-        // Generation of the anonymous avatar (Vizhash):
-        // If a nickname is provided, we generate a Vizhash.
-        // (We assume that if the user did not enter a nickname, he/she wants
-        // to be anonymous and we will not generate the vizhash.)
-        $vh = new vizhash16x16();
-        $pngdata = $vh->generate(trafficlimiter::getIp());
-        if ($pngdata != '')
+        if ($this->_conf->getKey('vizhash'))
         {
-            $this->_data->meta->vizhash = 'data:image/png;base64,' . base64_encode($pngdata);
+            // Generation of the anonymous avatar (Vizhash):
+            // If a nickname is provided, we generate a Vizhash.
+            // (We assume that if the user did not enter a nickname, he/she wants
+            // to be anonymous and we will not generate the vizhash.)
+            $vh = new vizhash16x16();
+            $pngdata = $vh->generate(trafficlimiter::getIp());
+            if ($pngdata != '')
+            {
+                $this->_data->meta->vizhash = 'data:image/png;base64,' . base64_encode($pngdata);
+            }
+            // Once the avatar is generated, we do not keep the IP address, nor its hash.
         }
-        // Once the avatar is generated, we do not keep the IP address, nor its hash.
     }
 }
diff --git a/lib/privatebin/db.php b/lib/privatebin/db.php
index 89ff7847..08b495e1 100644
--- a/lib/privatebin/db.php
+++ b/lib/privatebin/db.php
@@ -325,6 +325,13 @@ class privatebin_db extends privatebin_abstract
      */
     public function createComment($pasteid, $parentid, $commentid, $comment)
     {
+        foreach (array('nickname', 'vizhash') as $key)
+        {
+            if (!array_key_exists($key, $comment['meta']))
+            {
+                $comment['meta'][$key] = null;
+            }
+        }
         return self::_exec(
             'INSERT INTO ' . self::_sanitizeIdentifier('comment') .
             ' VALUES(?,?,?,?,?,?,?)',
@@ -367,9 +374,9 @@ class privatebin_db extends privatebin_abstract
                 $comments[$i]->data = $row['data'];
                 $comments[$i]->meta = new stdClass;
                 $comments[$i]->meta->postdate = (int) $row['postdate'];
-                if (array_key_exists('nickname', $row))
+                if (array_key_exists('nickname', $row) && !empty($row['nickname']))
                     $comments[$i]->meta->nickname = $row['nickname'];
-                if (array_key_exists('vizhash', $row))
+                if (array_key_exists('vizhash', $row) && !empty($row['vizhash']))
                     $comments[$i]->meta->vizhash = $row['vizhash'];
             }
             ksort($comments);
diff --git a/tst/model.php b/tst/model.php
index 8009f892..92f8b652 100644
--- a/tst/model.php
+++ b/tst/model.php
@@ -208,4 +208,59 @@ class modelTest extends PHPUnit_Framework_TestCase
         $paste->store();
         $paste->getComment(helper::getPasteId())->delete();
     }
+
+    public function testCommentWithDisabledVizhash()
+    {
+        $options = parse_ini_file(CONF, true);
+        $options['main']['vizhash'] = false;
+        $options['model'] = array(
+            'class' => 'privatebin_db',
+        );
+        $options['model_options'] = array(
+            'dsn' => 'sqlite::memory:',
+            'usr' => null,
+            'pwd' => null,
+            'opt' => array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION),
+        );
+        helper::confBackup();
+        helper::createIniFile(CONF, $options);
+        $model = new model(new configuration);
+
+        $pasteData = helper::getPaste();
+        $this->_model->getPaste(helper::getPasteId())->delete();
+        $paste = $model->getPaste(helper::getPasteId());
+        $this->assertFalse($paste->exists(), 'paste does not yet exist');
+
+        $paste = $model->getPaste();
+        $paste->setData($pasteData['data']);
+        $paste->setOpendiscussion();
+        $paste->setFormatter($pasteData['meta']['formatter']);
+        $paste->store();
+
+        $paste = $model->getPaste(helper::getPasteId());
+        $this->assertTrue($paste->exists(), 'paste exists after storing it');
+        $paste = $paste->get();
+        $this->assertEquals($pasteData['data'], $paste->data);
+        foreach (array('opendiscussion', 'formatter') as $key) {
+            $this->assertEquals($pasteData['meta'][$key], $paste->meta->$key);
+        }
+
+        // storing comments
+        $commentData = helper::getComment();
+        $paste = $model->getPaste(helper::getPasteId());
+        $comment = $paste->getComment(helper::getPasteId(), helper::getCommentId());
+        $this->assertFalse($comment->exists(), 'comment does not yet exist');
+
+        $comment = $paste->getComment(helper::getPasteId());
+        $comment->setData($commentData['data']);
+        $comment->setNickname($commentData['meta']['nickname']);
+        $comment->store();
+
+        $comment = $paste->getComment(helper::getPasteId(), helper::getCommentId());
+        $this->assertTrue($comment->exists(), 'comment exists after storing it');
+        $comment = $comment->get();
+        $this->assertEquals($commentData['data'], $comment->data);
+        $this->assertEquals($commentData['meta']['nickname'], $comment->meta->nickname);
+        $this->assertFalse(property_exists($comment->meta, 'vizhash'), 'vizhash was not generated');
+    }
 }