diff --git a/src/Symfony/Component/VarDumper/CHANGELOG.md b/src/Symfony/Component/VarDumper/CHANGELOG.md
index 24a5843f64..2d44cad225 100644
--- a/src/Symfony/Component/VarDumper/CHANGELOG.md
+++ b/src/Symfony/Component/VarDumper/CHANGELOG.md
@@ -5,6 +5,7 @@ CHANGELOG
 -----
 
  * added `AbstractCloner::setMinDepth()` function to ensure minimum tree depth
+ * deprecated `MongoCaster`
 
 2.7.0
 -----
diff --git a/src/Symfony/Component/VarDumper/Caster/MongoCaster.php b/src/Symfony/Component/VarDumper/Caster/MongoCaster.php
index 92258f06fa..2219386bc2 100644
--- a/src/Symfony/Component/VarDumper/Caster/MongoCaster.php
+++ b/src/Symfony/Component/VarDumper/Caster/MongoCaster.php
@@ -13,10 +13,14 @@ namespace Symfony\Component\VarDumper\Caster;
 
 use Symfony\Component\VarDumper\Cloner\Stub;
 
+@trigger_error('The '.__NAMESPACE__.'\MongoCaster class is deprecated since version 3.4 and will be removed in 4.0.', E_USER_DEPRECATED);
+
 /**
  * Casts classes from the MongoDb extension to array representation.
  *
  * @author Nicolas Grekas <p@tchwork.com>
+ *
+ * @deprecated since version 3.4, to be removed in 4.0.
  */
 class MongoCaster
 {