diff --git a/src/Monolog/Processor/TagProcessor.php b/src/Monolog/Processor/TagProcessor.php
index 2784cef4..2b6212e2 100644
--- a/src/Monolog/Processor/TagProcessor.php
+++ b/src/Monolog/Processor/TagProcessor.php
@@ -21,6 +21,16 @@ class TagProcessor
     private $tags;
 
     public function __construct(array $tags = array())
+    {
+        $this->setTags($tags);
+    }
+
+    public function addTags(array $tags = array())
+    {
+        $this->tags = array_values(array_unique(array_merge($this->tags, $tags)));
+    }
+
+    public function setTags(array $tags = array())
     {
         $this->tags = $tags;
     }
diff --git a/tests/Monolog/Processor/TagProcessorTest.php b/tests/Monolog/Processor/TagProcessorTest.php
index 851a9dc2..bf1659c5 100644
--- a/tests/Monolog/Processor/TagProcessorTest.php
+++ b/tests/Monolog/Processor/TagProcessorTest.php
@@ -26,4 +26,24 @@ class TagProcessorTest extends TestCase
 
         $this->assertEquals($tags, $record['extra']['tags']);
     }
+
+    /**
+     * @covers Monolog\Processor\TagProcessor::__invoke
+     */
+    public function testProcessorTagModification()
+    {
+        $tags = array(1, 2, 3);
+        $processor = new TagProcessor($tags);
+
+        $record = $processor($this->getRecord());
+        $this->assertEquals($tags, $record['extra']['tags']);
+
+        $processor->setTags(array('a', 'b'));
+        $record = $processor($this->getRecord());
+        $this->assertEquals(array('a', 'b'), $record['extra']['tags']);
+
+        $processor->addTags(array('a', 'c'));
+        $record = $processor($this->getRecord());
+        $this->assertEquals(array('a', 'b', 'c'), $record['extra']['tags']);
+    }
 }