diff --git a/app/Config/Autoload.php b/app/Config/Autoload.php
index e9ee6613d22b..22f05ecdab26 100644
--- a/app/Config/Autoload.php
+++ b/app/Config/Autoload.php
@@ -17,6 +17,8 @@
  *
  * NOTE: This class is required prior to Autoloader instantiation,
  *       and does not extend BaseConfig.
+ *
+ * @immutable
  */
 class Autoload extends AutoloadConfig
 {
diff --git a/app/Config/DocTypes.php b/app/Config/DocTypes.php
index 788d68fdc117..7e8aaacf09dd 100755
--- a/app/Config/DocTypes.php
+++ b/app/Config/DocTypes.php
@@ -2,6 +2,9 @@
 
 namespace Config;
 
+/**
+ * @immutable
+ */
 class DocTypes
 {
     /**
diff --git a/app/Config/ForeignCharacters.php b/app/Config/ForeignCharacters.php
index 174ddb16a872..f1a95725c5c7 100644
--- a/app/Config/ForeignCharacters.php
+++ b/app/Config/ForeignCharacters.php
@@ -4,6 +4,9 @@
 
 use CodeIgniter\Config\ForeignCharacters as BaseForeignCharacters;
 
+/**
+ * @immutable
+ */
 class ForeignCharacters extends BaseForeignCharacters
 {
 }
diff --git a/app/Config/Mimes.php b/app/Config/Mimes.php
index 99d28e5f8f86..d02df1aba796 100644
--- a/app/Config/Mimes.php
+++ b/app/Config/Mimes.php
@@ -15,6 +15,8 @@
  *
  * When working with mime types, please make sure you have the ´fileinfo´
  * extension enabled to reliably detect the media types.
+ *
+ * @immutable
  */
 class Mimes
 {
diff --git a/app/Config/Modules.php b/app/Config/Modules.php
index 54079e771f29..f84580c856d3 100644
--- a/app/Config/Modules.php
+++ b/app/Config/Modules.php
@@ -9,6 +9,8 @@
  *
  * NOTE: This class is required prior to Autoloader instantiation,
  *       and does not extend BaseConfig.
+ *
+ * @immutable
  */
 class Modules extends BaseModules
 {