diff --git a/requirements.txt b/requirements.txt
index 59c4d3a2..cb46dd4c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
 sqlalchemy
 radicale<3.0.0
 mysqlclient==2.0.1
-pymssql<3.0
+pymssql<=2.1.5