diff --git a/qubes/storage/__init__.py b/qubes/storage/__init__.py
index 5da497171..a5fbdb37f 100644
--- a/qubes/storage/__init__.py
+++ b/qubes/storage/__init__.py
@@ -238,6 +238,7 @@ async def start_encrypted(self, name):
         await qubes.utils.cryptsetup(
             "--key-file=/dev/urandom",
             "--cipher=aes-xts-plain64",
+            "--key-size=256",
             "--type=plain",
             "--",
             "open",