diff --git a/src/Connection.php b/src/Connection.php
index 343c0ca21..44bf58214 100644
--- a/src/Connection.php
+++ b/src/Connection.php
@@ -327,6 +327,12 @@ public function __call($method, $parameters)
         return $this->db->$method(...$parameters);
     }
 
+    /**
+     * Return the server version of one of the MongoDB servers: primary for
+     * replica sets and standalone, and the selected server for sharded clusters.
+     *
+     * @internal because this method is not part of the stable API.
+     */
     public function getServerVersion(): string
     {
         return $this->db->command(['buildInfo' => 1])->toArray()[0]['version'];