diff --git a/files/templates/casino/blackjack_screen.html b/files/templates/casino/blackjack_screen.html
index 91340915f..eca1ff7a2 100644
--- a/files/templates/casino/blackjack_screen.html
+++ b/files/templates/casino/blackjack_screen.html
@@ -4,6 +4,7 @@
 <script>
 	function makeBlackjackRequest(action) {
 		const xhr = new XMLHttpRequest();
+		xhr.setRequestHeader('xhr', 'xhr');
 		xhr.open("post", `/casino/twentyone/${action}`);
 		xhr.onload = handleBlackjackResponse.bind(null, xhr);
 		xhr.blackjackAction = action;