diff --git a/src/Message.php b/src/Message.php
index 5561a513..19054bed 100644
--- a/src/Message.php
+++ b/src/Message.php
@@ -10,6 +10,11 @@
 
 final class Message
 {
+    /**
+     * Default maximum allowed size of the short summary of the message body.
+     */
+    public const BODY_SUMMARY_TRUNCATE_AT = 120;
+
     /**
      * Returns the string representation of an HTTP message.
      *
@@ -53,7 +58,7 @@ public static function toString(MessageInterface $message): string
      * @param MessageInterface $message    The message to get the body summary
      * @param int              $truncateAt The maximum allowed size of the summary
      */
-    public static function bodySummary(MessageInterface $message, int $truncateAt = 120): ?string
+    public static function bodySummary(MessageInterface $message, int $truncateAt = self::BODY_SUMMARY_TRUNCATE_AT): ?string
     {
         $body = $message->getBody();