diff --git a/.github/.OwlBot.lock.yaml b/.github/.OwlBot.lock.yaml
index 127c2cd..da616c9 100644
--- a/.github/.OwlBot.lock.yaml
+++ b/.github/.OwlBot.lock.yaml
@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/repo-automation-bots/owlbot-python:latest
-  digest: sha256:0856ca711da1fd5ec9d6d7da6c50aa0bbf550fb94acb47b55159a640791987bf
+  digest: sha256:c66ba3c8d7bc8566f47df841f98cd0097b28fff0b1864c86f5817f4c8c3e8600
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6e3fcf7..5422508 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,12 @@
 # Changelog
 
+### [0.2.1](https://www.github.com/googleapis/python-artifact-registry/compare/v0.2.0...v0.2.1) (2021-06-01)
+
+
+### Bug Fixes
+
+* **deps:** add packaging requirement ([#33](https://www.github.com/googleapis/python-artifact-registry/issues/33)) ([ca2907e](https://www.github.com/googleapis/python-artifact-registry/commit/ca2907efdcd05a88a63c798a367baa71f2fb78b4))
+
 ## [0.2.0](https://www.github.com/googleapis/python-artifact-registry/compare/v0.1.0...v0.2.0) (2021-05-25)
 
 
diff --git a/docs/conf.py b/docs/conf.py
index c8203df..f12c971 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -363,6 +363,7 @@
     "google.api_core": ("https://googleapis.dev/python/google-api-core/latest/", None,),
     "grpc": ("https://grpc.github.io/grpc/python/", None),
     "proto-plus": ("https://proto-plus-python.readthedocs.io/en/latest/", None),
+    "protobuf": ("https://googleapis.dev/python/protobuf/latest/", None),
 }
 
 
diff --git a/setup.py b/setup.py
index 8c7b9c0..375434b 100644
--- a/setup.py
+++ b/setup.py
@@ -20,7 +20,7 @@
 import setuptools  # type: ignore
 
 name = "google-cloud-artifact-registry"
-version = "0.2.0"
+version = "0.2.1"
 description = "Artifact Registry API client library"
 release_status = "Development Status :: 4 - Beta"
 url = "https://github.com/googleapis/python-artifact-registry"
@@ -28,6 +28,7 @@
     "google-api-core[grpc] >= 1.22.2, < 2.0.0dev",
     "libcst >= 0.2.5",
     "proto-plus >= 1.4.0",
+    "packaging >= 14.3",
     "grpc-google-iam-v1",
 ]
 
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index e58b08e..477e2dc 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -23,3 +23,5 @@ google-api-core==1.22.2
 grpc-google-iam-v1==0.12.3
 libcst==0.2.5
 proto-plus==1.4.0
+packaging==14.3
+google-auth==1.24.0  # TODO: remove when google-auth>=1.25.0 si transitively required through google-api-core