diff --git a/PhutilMediaWikiAuthAdapter.php b/PhutilMediaWikiAuthAdapter.php
index 0bd6a5b..599ef08 100644
--- a/PhutilMediaWikiAuthAdapter.php
+++ b/PhutilMediaWikiAuthAdapter.php
@@ -118,6 +118,7 @@ private function getUserInfo() {
       list( $body ) = $this->newOAuth1Future( $uri )
         ->setMethod( 'GET' )
         ->setNonce( $nonce )
+        ->addHeader( 'User-Agent', __CLASS__ )
         ->resolvex();
       $this->userinfo = $this->decodeAndVerifyJWT( $body, $nonce );
     }