diff --git a/src/app.html b/src/app.html
index 935dc22..f438cea 100644
--- a/src/app.html
+++ b/src/app.html
@@ -25,7 +25,7 @@
 
 		ym(88895893, "getClientID", function (clientID) {
 			ym(88895893, 'userParams', {
-				university_test_group: clientID % 2 === 0 ? 'a' : 'b'
+				university_test_group: Number(BigInt(clientID).toString().slice(-1)) % 2 === 0 ? 'a' : 'b'
 			});
 		});
 	</script>