diff --git a/radicale/auth/htpasswd.py b/radicale/auth/htpasswd.py
index aebad2a3..587d08a4 100644
--- a/radicale/auth/htpasswd.py
+++ b/radicale/auth/htpasswd.py
@@ -136,7 +136,7 @@ class Auth(auth.BaseAuth):
         if self._encryption == "argon2" or self._encryption == "autodetect":
             try:
                 import argon2
-                from passlib.hash import argon2
+                from passlib.hash import argon2 # noqa: F811 (required to detect missing argon2-cffi)
             except ImportError as e:
                 if (self._encryption == "autodetect") and (self._htpasswd_argon2_use == 0):
                     logger.warning("auth htpasswd encryption is 'radicale.auth.htpasswd_encryption.%s' which can require argon2 module, but currently no entries found", self._encryption)
diff --git a/radicale/tests/test_auth.py b/radicale/tests/test_auth.py
index 91dbbcf9..52d1f536 100644
--- a/radicale/tests/test_auth.py
+++ b/radicale/tests/test_auth.py
@@ -52,7 +52,7 @@ class TestBaseAuthRequests(BaseTest):
     # test for available argon2 module
     try:
         import argon2
-        from passlib.hash import argon2
+        from passlib.hash import argon2 # noqa: F811 (required to detect missing argon2-cffi)
     except ImportError:
         has_argon2 = 0
     else: