diff --git a/plugins/wallabag/wallabag.php b/plugins/wallabag/wallabag.php
index db8151c..024a3d2 100644
--- a/plugins/wallabag/wallabag.php
+++ b/plugins/wallabag/wallabag.php
@@ -1,25 +1,33 @@
 <?php
 
+/**
+ * Plugin Wallabag.
+ */
+
 // don't raise unnecessary warnings
 if (is_file(PluginManager::$PLUGINS_PATH . '/wallabag/config.php')) {
     include PluginManager::$PLUGINS_PATH . '/wallabag/config.php';
 }
 
 if (!isset($GLOBALS['plugins']['WALLABAG_URL'])) {
-    header('Content-Type: text/plain; charset=utf-8');
-    echo 'Wallabag plugin error: '. PHP_EOL;
-    echo '  Please copy "plugins/wallabag/config.php.dist" to config.php and configure your Wallabag URL.'. PHP_EOL;
-    echo '  You can also define "$GLOBALS[\'plugins\'][\'WALLABAG_URL\']" in your global Shaarli config.php file.';
-    exit;
+    $GLOBALS['plugins']['errors'][] = 'Wallabag plugin error: '.
+        'Please define "$GLOBALS[\'plugins\'][\'WALLABAG_URL\']" '.
+        'in "plugins/wallabag/config.php" or in your Shaarli config.php file.';
 }
 
 /**
  * Add wallabag icon to link_plugin when rendering linklist.
  *
- * @param $data - linklist data.
+ * @param mixed $data - linklist data.
+ *
  * @return mixed - linklist data with wallabag plugin.
  */
-function hook_wallabag_render_linklist($data) {
+function hook_wallabag_render_linklist($data)
+{
+    if (!isset($GLOBALS['plugins']['WALLABAG_URL'])) {
+        return $data;
+    }
+
     $wallabag_html = file_get_contents(PluginManager::$PLUGINS_PATH . '/wallabag/wallabag.html');
 
     foreach ($data['links'] as &$value) {
diff --git a/tests/plugins/PluginWallabagTest.php b/tests/plugins/PluginWallabagTest.php
new file mode 100644
index 0000000..7cc83f4
--- /dev/null
+++ b/tests/plugins/PluginWallabagTest.php
@@ -0,0 +1,49 @@
+<?php
+
+/**
+ * PluginWallabagTest.php.php
+ */
+
+require_once 'plugins/wallabag/wallabag.php';
+
+/**
+ * Class PluginWallabagTest
+ * Unit test for the Wallabag plugin
+ */
+class PluginWallabagTest extends PHPUnit_Framework_TestCase
+{
+    /**
+     * Reset plugin path
+     */
+    function setUp()
+    {
+        PluginManager::$PLUGINS_PATH = 'plugins';
+    }
+
+    /**
+     * Test render_linklist hook.
+     */
+    function testWallabagLinklist()
+    {
+        $GLOBALS['plugins']['WALLABAG_URL'] = 'value';
+        $str = 'http://randomstr.com/test';
+        $data = array(
+            'title' => $str,
+            'links' => array(
+                array(
+                    'url' => $str,
+                )
+            )
+        );
+
+        $data = hook_wallabag_render_linklist($data);
+        $link = $data['links'][0];
+        // data shouldn't be altered
+        $this->assertEquals($str, $data['title']);
+        $this->assertEquals($str, $link['url']);
+
+        // plugin data
+        $this->assertEquals(1, count($link['link_plugin']));
+        $this->assertNotFalse(strpos($link['link_plugin'][0], $str));
+    }
+}