diff --git a/synapse/tests/test_lib_hiveauth.py b/synapse/tests/test_lib_hiveauth.py
index d3fa4714f8e..48f23d92fe8 100644
--- a/synapse/tests/test_lib_hiveauth.py
+++ b/synapse/tests/test_lib_hiveauth.py
@@ -484,6 +484,9 @@ async def test_hive_auth_password_policy(self):
             )
 
         policy = {
+            # The complexity requirements here allow for empty passwords or
+            # passwords that are ASCII only (no unicode) minus comma
+            # and period from the special character set.
             'complexity': {
                 'length': 0,
                 'upper:count': 2,