diff --git a/src/_zkapauthorizer/tests/fixtures.py b/src/_zkapauthorizer/tests/fixtures.py
index 20b05922495aefce85e12a69941276836840950a..dbb49e6568cae998024e71c866e67e40c88b089f 100644
--- a/src/_zkapauthorizer/tests/fixtures.py
+++ b/src/_zkapauthorizer/tests/fixtures.py
@@ -1,3 +1,21 @@
+# Copyright 2019 PrivateStorage.io, LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Common fixtures to let the test suite focus on application logic.
+"""
+
 from __future__ import (
     absolute_import,
 )
diff --git a/src/_zkapauthorizer/tests/privacypass.py b/src/_zkapauthorizer/tests/privacypass.py
index 9b46fe3832bf1ce57a6852037e9bca5c3fb1fb37..63c1f4386652cc8cb5432e0d522966878c7f926b 100644
--- a/src/_zkapauthorizer/tests/privacypass.py
+++ b/src/_zkapauthorizer/tests/privacypass.py
@@ -1,3 +1,21 @@
+# Copyright 2019 PrivateStorage.io, LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Ristretto-flavored PrivacyPass helpers for the test suite.
+"""
+
 from __future__ import (
     absolute_import,
 )
@@ -8,6 +26,21 @@ from privacypass import (
 )
 
 def make_passes(signing_key, for_message, random_tokens):
+    """
+    Create a number of cryptographically correct privacy passes.
+
+    :param privacypass.SigningKey signing_key: The key to use to sign the
+        passes.
+
+    :param unicode for_message: The request-binding message with which to
+        associate the passes.
+
+    :param list[privacypass.RandomToken] random_tokens: The random tokens to
+        feed in to the pass generation process.
+
+    :return list[unicode]: The privacy passes.  The returned list has one
+        element for each element of ``random_tokens``.
+    """
     blinded_tokens = list(
         token.blind()
         for token