diff --git a/src/Monolog/Processor/WebProcessor.php b/src/Monolog/Processor/WebProcessor.php
index 88a9a04c..7021dcf7 100644
--- a/src/Monolog/Processor/WebProcessor.php
+++ b/src/Monolog/Processor/WebProcessor.php
@@ -35,9 +35,10 @@ class WebProcessor
     );
 
     /**
-     * @param mixed $serverData array or object w/ ArrayAccess that provides access to the $_SERVER data
+     * @param mixed      $serverData  Array or object w/ ArrayAccess that provides access to the $_SERVER data
+     * @param array|null $extraFields Extra field names to be added (all available by default)
      */
-    public function __construct($serverData = null)
+    public function __construct($serverData = null, array $extraFields = null)
     {
         if (null === $serverData) {
             $this->serverData =& $_SERVER;
@@ -46,6 +47,14 @@ class WebProcessor
         } else {
             throw new \UnexpectedValueException('$serverData must be an array or object implementing ArrayAccess.');
         }
+
+        if (null !== $extraFields) {
+            foreach (array_keys($this->extraFields) as $fieldName) {
+                if (!in_array($fieldName, $extraFields)) {
+                    unset($this->extraFields[$fieldName]);
+                }
+            }
+        }
     }
 
     /**
diff --git a/tests/Monolog/Processor/WebProcessorTest.php b/tests/Monolog/Processor/WebProcessorTest.php
index df29fdd6..dba89412 100644
--- a/tests/Monolog/Processor/WebProcessorTest.php
+++ b/tests/Monolog/Processor/WebProcessorTest.php
@@ -73,6 +73,21 @@ class WebProcessorTest extends TestCase
         $this->assertFalse(isset($record['extra']['unique_id']));
     }
 
+    public function testProcessorAddsOnlyRequestedExtraFields()
+    {
+        $server = array(
+            'REQUEST_URI'    => 'A',
+            'REMOTE_ADDR'    => 'B',
+            'REQUEST_METHOD' => 'C',
+            'SERVER_NAME'    => 'F',
+        );
+
+        $processor = new WebProcessor($server, array('url', 'http_method'));
+        $record = $processor($this->getRecord());
+
+        $this->assertSame(array('url' => 'A', 'http_method' => 'C'), $record['extra']);
+    }
+
     /**
      * @expectedException UnexpectedValueException
      */