diff --git a/src/wp-includes/class-wp-locale.php b/src/wp-includes/class-wp-locale.php
index e8dcfc6488..a8a00f4409 100644
--- a/src/wp-includes/class-wp-locale.php
+++ b/src/wp-includes/class-wp-locale.php
@@ -59,6 +59,14 @@ class WP_Locale {
 	 */
 	public $month;
 
+	/**
+	 * Stores the translated strings for the month names in genitive case, if the locale specifies.
+	 *
+	 * @since 4.4.0
+	 * @var array
+	 */
+	public $month_genitive;
+
 	/**
 	 * Stores the translated strings for the abbreviated month names.
 	 *