diff --git a/libraries/src/Language/LanguageStemmer.php b/libraries/src/Language/LanguageStemmer.php
index 1d04b367421ee..0f27e1e203098 100644
--- a/libraries/src/Language/LanguageStemmer.php
+++ b/libraries/src/Language/LanguageStemmer.php
@@ -13,7 +13,8 @@
 /**
  * Stemmer base class.
  *
- * @since  3.0.0
+ * @since       3.0.0
+ * @deprecated  4.0 Use wamania/php-stemmer
  */
 abstract class LanguageStemmer
 {
diff --git a/libraries/src/Language/Stemmer/Porteren.php b/libraries/src/Language/Stemmer/Porteren.php
index 6ccd3b7c85445..837bd0aef755a 100644
--- a/libraries/src/Language/Stemmer/Porteren.php
+++ b/libraries/src/Language/Stemmer/Porteren.php
@@ -19,7 +19,8 @@
  * This class was adapted from one written by Richard Heyes.
  * See copyright and link information above.
  *
- * @since  3.0.0
+ * @since       3.0.0
+ * @deprecated  4.0 Use wamania/php-stemmer
  */
 class Porteren extends LanguageStemmer
 {