diff --git a/components/yaml.rst b/components/yaml.rst
index a04ad7afe35..b7ceec4e25a 100644
--- a/components/yaml.rst
+++ b/components/yaml.rst
@@ -293,6 +293,17 @@ flag::
     //       Line
     //       String
 
+Parsing PHP Constants
+~~~~~~~~~~~~~~~~~~~~~
+
+By default, the YAML parser treats the PHP constants included in the contents as
+regular strings. Use the ``PARSE_CONSTANT`` flag and the special ``!php/const:``
+syntax to parse them as proper PHP constants::
+
+    $yaml = '{ foo: PHP_INT_SIZE, bar: !php/const:PHP_INT_SIZE }';
+    $parameters = Yaml::parse($yaml, Yaml::PARSE_CONSTANT);
+    // $parameters = array('foo' => 'PHP_INT_SIZE', 'bar' => 8);
+
 Syntax Validation
 ~~~~~~~~~~~~~~~~~