diff --git a/radicale/utils.py b/radicale/utils.py
index 11f8ab17..e0ae92a0 100644
--- a/radicale/utils.py
+++ b/radicale/utils.py
@@ -29,6 +29,7 @@ _T_co = TypeVar("_T_co", covariant=True)
 
 RADICALE_MODULES: Sequence[str] = ("radicale", "vobject", "passlib", "defusedxml",
                                    "bcrypt",
+                                   "argon2-cffi",
                                    "pika",
                                    "ldap",
                                    "ldap3",