diff --git a/requirements.txt b/requirements.txt
index aad665e..b423f95 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-tornado==6.5
+tornado==6.4.2
 isodate==0.7.2
 pytest==8.3.5
 schwifty==2025.1.0