diff --git a/DependencyInjection/Configuration.php b/DependencyInjection/Configuration.php
index 9412b24..708f3b2 100644
--- a/DependencyInjection/Configuration.php
+++ b/DependencyInjection/Configuration.php
@@ -24,6 +24,7 @@ public function getConfigTreeBuilder()
                 ->arrayNode('application')->isRequired()
                     ->children()
                         ->scalarNode('name')->defaultNull()->cannotBeEmpty()->end()
+                        ->scalarNode('locale')->defaultNull()->end()
                     ->end()
                 ->end()
                 ->arrayNode('handlers')->isRequired()
diff --git a/DependencyInjection/DeamonLoggerExtraExtension.php b/DependencyInjection/DeamonLoggerExtraExtension.php
index 743c6d4..d6d05e3 100644
--- a/DependencyInjection/DeamonLoggerExtraExtension.php
+++ b/DependencyInjection/DeamonLoggerExtraExtension.php
@@ -27,7 +27,8 @@ public function load(array $configs, ContainerBuilder $container)
         $loader->load('processors.xml');
 
         $definition = $container->getDefinition('deamon.logger_extra.context');
-        $definition->replaceArgument(1, $config['application']['name']);
+        $definition->replaceArgument(0, $config['application']['name']);
+        $definition->addArgument($config['application']['locale']);
 
         $definition = $container->getDefinition('deamon.logger_extra.processors.web_processor');
         $definition->replaceArgument(0, $config['config']);
diff --git a/Processors/Monolog/DeamonLoggerExtraWebProcessor.php b/Processors/Monolog/DeamonLoggerExtraWebProcessor.php
index c4377e2..932354d 100644
--- a/Processors/Monolog/DeamonLoggerExtraWebProcessor.php
+++ b/Processors/Monolog/DeamonLoggerExtraWebProcessor.php
@@ -137,7 +137,7 @@ private function addUserInfo()
     }
 
     /**
-     * append method result of user object
+     * append method result of user object.
      *
      * @param $user
      */
@@ -151,7 +151,7 @@ private function appendUserMethodInfo($user)
     }
 
     /**
-     * Check if passed token is an instance of TokenInterface and an instance of config UserClass
+     * Check if passed token is an instance of TokenInterface and an instance of config UserClass.
      *
      * @param $token
      *
@@ -182,7 +182,7 @@ private function addChannelInfo()
      */
     private function addInfo($key, $value)
     {
-        if ($this->configShowExtraInfo($key)) {
+        if ($this->configShowExtraInfo($key) && $value !== null) {
             $this->record['extra'][$key] = $value;
         }
     }
diff --git a/README.md b/README.md
index d8fb7e4..d69ad69 100644
--- a/README.md
+++ b/README.md
@@ -89,7 +89,8 @@ deamon_logger_extra:
 // app/config/config.yml
 deamon_logger_extra:
     application:
-        name: "loc-deamonfront" # default to null 
+        name: "loc-deamonfront" # default to null
+        locale: "fr" # default to null
     handlers: [default_info] # the only required field
     config:
         channel_prefix: "v0.1" # default to null
diff --git a/Resources/config/services.xml b/Resources/config/services.xml
index 1062a6b..4df1903 100644
--- a/Resources/config/services.xml
+++ b/Resources/config/services.xml
@@ -9,7 +9,6 @@
     </parameters>
     <services>
         <service id="deamon.logger_extra.context" class="%deamon.logger_extra.context.class%">
-            <argument type="string">%locale%</argument>
             <argument />
         </service>
     </services>
diff --git a/Services/DeamonLoggerExtraContext.php b/Services/DeamonLoggerExtraContext.php
index 902370c..564f127 100644
--- a/Services/DeamonLoggerExtraContext.php
+++ b/Services/DeamonLoggerExtraContext.php
@@ -7,10 +7,10 @@ class DeamonLoggerExtraContext
     private $locale;
     private $applicationName;
 
-    public function __construct($locale, $applicationName)
+    public function __construct($applicationName, $locale = null)
     {
-        $this->locale = $locale;
         $this->applicationName = $applicationName;
+        $this->locale = $locale;
     }
 
     public function getLocale()
diff --git a/Tests/DependencyInjection/DeamonLoggerExtraExtensionTest.php b/Tests/DependencyInjection/DeamonLoggerExtraExtensionTest.php
index e966fb4..d164dc7 100644
--- a/Tests/DependencyInjection/DeamonLoggerExtraExtensionTest.php
+++ b/Tests/DependencyInjection/DeamonLoggerExtraExtensionTest.php
@@ -42,7 +42,9 @@ public function testLoad()
         $this->assertTrue($this->container->hasDefinition('deamon.logger_extra.processors.web_processor'));
 
         $definition1 = $this->container->getDefinition('deamon.logger_extra.context');
-        $this->assertEquals('foo', $definition1->getArgument(1));
+        $this->assertEquals('foo', $definition1->getArgument(0));
+        $this->assertCount(2, $definition1->getArguments());
+        $this->assertEquals('fr', $definition1->getArgument(1));
 
         $definition2 = $this->container->getDefinition('deamon.logger_extra.processors.web_processor');
         $this->assertEquals($configs[0]['config'], $definition2->getArgument(0));
@@ -84,6 +86,8 @@ public function testDefaultValue()
         $this->assertTrue($this->container->hasDefinition('deamon.logger_extra.processors.web_processor'));
 
         $definition1 = $this->container->getDefinition('deamon.logger_extra.context');
+        $this->assertNull($definition1->getArgument(0));
+        $this->assertCount(2, $definition1->getArguments());
         $this->assertNull($definition1->getArgument(1));
 
         $definition2 = $this->container->getDefinition('deamon.logger_extra.processors.web_processor');
@@ -120,6 +124,7 @@ private function getValidConfigFull()
         return [
             'application' => [
                 'name' => 'foo',
+                'locale' => 'fr',
             ],
             'handlers' => ['bar'],
             'config' => [
diff --git a/Tests/Processors/Monolog/DeamonLoggerExtraWebProcessorTest.php b/Tests/Processors/Monolog/DeamonLoggerExtraWebProcessorTest.php
index 4fdc0eb..41bbb9e 100644
--- a/Tests/Processors/Monolog/DeamonLoggerExtraWebProcessorTest.php
+++ b/Tests/Processors/Monolog/DeamonLoggerExtraWebProcessorTest.php
@@ -44,6 +44,27 @@ public function testAddContextInfo()
         $this->assertArrayHasKeyAndEquals('application', $record['extra'], 'foo_app');
     }
 
+    /**
+     * @runInSeparateProcess
+     */
+    public function testAddContextInfoWithoutLocale()
+    {
+        $config = $this->getDisplayConfig([
+            'env' => true,
+            'locale' => true,
+            'application_name' => true,
+        ]);
+
+        $processor = new DeamonLoggerExtraWebProcessor($config);
+        $processor->setLoggerExtraContext($this->getLoggerExtraContext(null));
+        $processor->setEnvironment('env_foo');
+        $record = $processor->__invoke($this->getRecord());
+
+        $this->assertArrayHasKeyAndEquals('env', $record['extra'], 'env_foo');
+        $this->assertArrayNotHasKey('locale', $record['extra'], 'fr');
+        $this->assertArrayHasKeyAndEquals('application', $record['extra'], 'foo_app');
+    }
+
     public function testAddRequestInfo()
     {
         $config = $this->getDisplayConfig(
@@ -226,9 +247,9 @@ private function getRequestStack()
         return $stack;
     }
 
-    private function getLoggerExtraContext()
+    private function getLoggerExtraContext($locale = 'fr')
     {
-        return new DeamonLoggerExtraContext('fr', 'foo_app');
+        return new DeamonLoggerExtraContext('foo_app', $locale);
     }
 
     private function getTokenStorage(UserInterface $user = null)
diff --git a/Tests/Services/DeamonLoggerExtraContextTest.php b/Tests/Services/DeamonLoggerExtraContextTest.php
index f17e849..66b6f5b 100644
--- a/Tests/Services/DeamonLoggerExtraContextTest.php
+++ b/Tests/Services/DeamonLoggerExtraContextTest.php
@@ -10,11 +10,11 @@ class DeamonLoggerExtraContextTest extends TestCase
     /**
      * @dataProvider getLocaleDataset
      *
-     * @param $locale
+     * @param string $locale
      */
     public function testGetLocale($locale)
     {
-        $context = new DeamonLoggerExtraContext($locale, '');
+        $context = new DeamonLoggerExtraContext('', $locale);
         $this->assertEquals($locale, $context->getLocale(), sprintf('locale should be %s, %s returned.', $locale, $context->getLocale()));
     }
 
@@ -33,7 +33,7 @@ public function getLocaleDataset()
      */
     public function testGetApplicationName($applicationName)
     {
-        $context = new DeamonLoggerExtraContext('fr', $applicationName);
+        $context = new DeamonLoggerExtraContext($applicationName, 'fr');
         $this->assertEquals($applicationName, $context->getApplicationName(), sprintf('application_name should be %s, %s returned.', $applicationName, $context->getApplicationName()));
     }