diff --git a/UPGRADE-3.4.md b/UPGRADE-3.4.md
index f72652fbe4..5a677088ac 100644
--- a/UPGRADE-3.4.md
+++ b/UPGRADE-3.4.md
@@ -50,6 +50,8 @@ DependencyInjection
 
  * Top-level anonymous services in XML are deprecated and will throw an exception in Symfony 4.0.
 
+ * Case insensitivity of parameter names is deprecated and will be removed in 4.0.
+
 Debug
 -----