diff --git a/config.ini-example b/config.ini-example
index 5c2aa51..30bd699 100644
--- a/config.ini-example
+++ b/config.ini-example
@@ -32,3 +32,8 @@ title = ""
 [date]
 ; timezone = UTC
 ; format = 'd/m/Y H:i:s'
+
+; custom avatar service
+[avatar]
+; url = '//gravatar.com/avatar/'
+; query[] = 'd=identicon'
\ No newline at end of file
diff --git a/src/Application.php b/src/Application.php
index f538a77..4217d31 100644
--- a/src/Application.php
+++ b/src/Application.php
@@ -37,6 +37,8 @@ class Application extends SilexApplication
         $this['filetypes'] = $config->getSection('filetypes');
         $this['binary_filetypes'] = $config->getSection('binary_filetypes');
         $this['cache.archives'] = $this->getCachePath() . 'archives';
+        $this['avatar.url'] = $config->get('avatar', 'url');
+        $this['avatar.query'] = $config->get('avatar', 'query');
 
         // Register services
         $this->register(new TwigServiceProvider(), array(
@@ -67,6 +69,7 @@ class Application extends SilexApplication
             $twig->addFilter(new \Twig_SimpleFilter('md5', 'md5'));
             $twig->addFilter(new \Twig_SimpleFilter('format_date', array($app, 'formatDate')));
             $twig->addFilter(new \Twig_SimpleFilter('format_size', array($app, 'formatSize')));
+            $twig->addFunction(new \Twig_SimpleFunction('avatar', array($app, 'getAvatar')));
 
             return $twig;
         }));
@@ -107,6 +110,18 @@ class Application extends SilexApplication
         return round($size, 2) . $units[$i];
     }
 
+    public function getAvatar($email, $size)
+    {
+        $url = $this['avatar.url'] ? $this['avatar.url'] : "//gravatar.com/avatar/";
+        $query = array("s=$size");
+        if (is_string($this['avatar.query']))
+            $query[] = $this['avatar.query'];
+        else if (is_array($this['avatar.query']))
+            $query = array_merge($query, $this['avatar.query']);
+        $id = md5(strtolower($email));
+        return $url . $id . "?" . implode('&', $query);
+    }
+
     public function getPath()
     {
         return $this->path . DIRECTORY_SEPARATOR;
diff --git a/src/Controller/NetworkController.php b/src/Controller/NetworkController.php
index 70f339f..27f8a19 100644
--- a/src/Controller/NetworkController.php
+++ b/src/Controller/NetworkController.php
@@ -46,10 +46,7 @@ class NetworkController implements ControllerProviderInterface
                         'author' => array(
                             'name' => $commit->getAuthor()->getName(),
                             'email' => $commit->getAuthor()->getEmail(),
-                            // due to the lack of a inbuilt javascript md5 mechanism, build the full avatar url on the php side
-                            'image' => '//gravatar.com/avatar/' . md5(
-                                strtolower($commit->getAuthor()->getEmail())
-                            ) . '?s=40'
+                            'image' => $app->getAvatar($commit->getAuthor()->getEmail(), 40)
                         )
                     );
                 }
diff --git a/themes/bootstrap3/twig/commit.twig b/themes/bootstrap3/twig/commit.twig
index 7293935..7a9863e 100644
--- a/themes/bootstrap3/twig/commit.twig
+++ b/themes/bootstrap3/twig/commit.twig
@@ -17,7 +17,7 @@
             {% if commit.body is not empty %}
             <p>{{ commit.body | nl2br }}</p>
             {% endif %}
-            <img src="https://gravatar.com/avatar/{{ commit.author.email | lower | md5 }}?s=32" class="pull-left space-right" />
+            <img src="{{ avatar(commit.author.email, 32) }}" class="pull-left space-right" />
             <span>
                 <a href="mailto:{{ commit.author.email }}">{{ commit.author.name }}</a> authored on {{ commit.date | format_date }}
                 {% if commit.author.email != commit.commiter.email %}
diff --git a/themes/bootstrap3/twig/commits_list.twig b/themes/bootstrap3/twig/commits_list.twig
index ba9057b..dd09c2e 100644
--- a/themes/bootstrap3/twig/commits_list.twig
+++ b/themes/bootstrap3/twig/commits_list.twig
@@ -9,7 +9,7 @@
     <tbody>
         {% for item in commit %}
         <tr>
-            <td width="5%"><img src="https://gravatar.com/avatar/{{ item.author.email | lower | md5 }}?s=40" /></td>
+            <td width="5%"><img src="{{ avatar(item.author.email, 40) }}" /></td>
             <td width="95%">
                 <span class="pull-right"><a class="btn btn-default btn-sm" href="{{ path('commit', {repo: repo, commit: item.hash}) }}"><span class="fa fa-list-alt"></span> View {{ item.shortHash }}</a></span>
                 <h4>{{ item.message }}</h4>
diff --git a/themes/default/twig/commit.twig b/themes/default/twig/commit.twig
index 495a1ce..c80a05f 100644
--- a/themes/default/twig/commit.twig
+++ b/themes/default/twig/commit.twig
@@ -16,7 +16,7 @@
             {% if commit.body is not empty %}
             <p>{{ commit.body | nl2br }}</p>
             {% endif %}
-            <img src="https://gravatar.com/avatar/{{ commit.author.email | lower | md5 }}?s=32" class="pull-left space-right" />
+            <img src="{{ avatar(commit.author.email, 32) }}" class="pull-left space-right" />
             <span>
                 <a href="mailto:{{ commit.author.email }}">{{ commit.author.name }}</a> authored on {{ commit.date | format_date }}
                 {% if commit.author.email != commit.commiter.email %}
diff --git a/themes/default/twig/commits_list.twig b/themes/default/twig/commits_list.twig
index 619bc97..6521276 100644
--- a/themes/default/twig/commits_list.twig
+++ b/themes/default/twig/commits_list.twig
@@ -9,7 +9,7 @@
     <tbody>
         {% for item in commit %}
         <tr>
-            <td width="5%"><img src="https://gravatar.com/avatar/{{ item.author.email | lower | md5 }}?s=40" /></td>
+            <td width="5%"><img src="{{ avatar( item.author.email, 40 ) }}" /></td>
             <td width="95%">
                 <span class="pull-right"><a class="btn btn-small" href="{{ path('commit', {repo: repo, commit: item.hash}) }}"><i class="icon-list-alt"></i> View {{ item.shortHash }}</a></span>
                 <h4>{{ item.message }}</h4>