diff --git a/.github/workflows/cd.yml b/.github/workflows/cd.yml
index 93b246ab8..de32c8df5 100644
--- a/.github/workflows/cd.yml
+++ b/.github/workflows/cd.yml
@@ -36,7 +36,7 @@ jobs:
         with:
           python-version: ${{ env.PYTHON_DEFAULT_VERSION }}
       - name: Install dependencies
-        run: python -m pip install --upgrade nox pdm==2.26.2
+        run: python -m pip install --upgrade nox pdm==2.26.4
       - name: Build the distribution
         id: build
         run: nox -vs build
@@ -79,7 +79,7 @@ jobs:
         run: |
           sudo apt-get -y update
           sudo apt-get -y install patchelf scons
-          python -m pip install --upgrade nox pdm==2.26.2
+          python -m pip install --upgrade nox pdm==2.26.4
           git config --global --add safe.directory '*'
       - name: Bundle the distribution
         id: bundle
@@ -114,7 +114,7 @@ jobs:
         with:
           python-version: ${{ env.PYTHON_DEFAULT_VERSION }}
       - name: Install dependencies
-        run: python -m pip install --upgrade nox pdm==2.26.2
+        run: python -m pip install --upgrade nox pdm==2.26.4
       - name: Bundle the distribution
         id: bundle
         shell: bash
@@ -159,7 +159,7 @@ jobs:
         with:
           python-version: ${{ env.PYTHON_DEFAULT_VERSION }}
       - name: Install dependencies
-        run: python -m pip install --upgrade nox pdm==2.26.2
+        run: python -m pip install --upgrade nox pdm==2.26.4
       - name: Build Dockerfile
         run: nox -vs generate_dockerfile
       - name: Set up QEMU
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0aefc4b9b..d02ff5bc4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -25,7 +25,7 @@ jobs:
         with:
           python-version: ${{ env.PYTHON_DEFAULT_VERSION }}
       - name: Install dependencies
-        run: python -m pip install --upgrade nox pdm==2.26.2
+        run: python -m pip install --upgrade nox pdm==2.26.4
       - name: Run linters
         run: nox -vs lint
       - name: Validate new changelog entries
@@ -47,7 +47,7 @@ jobs:
         with:
           python-version: ${{ env.PYTHON_DEFAULT_VERSION }}
       - name: Install dependencies
-        run: python -m pip install --upgrade nox pdm==2.26.2
+        run: python -m pip install --upgrade nox pdm==2.26.4
       - name: Build the distribution
         run: nox -vs build
   cleanup_buckets:
@@ -70,7 +70,7 @@ jobs:
           cache: "pip"
       - name: Install dependencies
         if: ${{ env.B2_TEST_APPLICATION_KEY != '' && env.B2_TEST_APPLICATION_KEY_ID != '' }}  # TODO: skip this whole job instead
-        run: python -m pip install --upgrade nox pdm==2.26.2
+        run: python -m pip install --upgrade nox pdm==2.26.4
       - name: Find and remove old buckets
         if: ${{ env.B2_TEST_APPLICATION_KEY != '' && env.B2_TEST_APPLICATION_KEY_ID != '' }}  # TODO: skip this whole job instead
         run: nox -vs cleanup_buckets
@@ -111,7 +111,7 @@ jobs:
         run: |
           brew install fish
       - name: Install dependencies
-        run: python -m pip install --upgrade nox pdm==2.26.2
+        run: python -m pip install --upgrade nox pdm==2.26.4
       - name: Run unit tests
         run: nox -vs unit -p ${{ matrix.python-version }}
       - name: Run integration tests (without secrets)
@@ -137,7 +137,7 @@ jobs:
         with:
           python-version: ${{ env.PYTHON_DEFAULT_VERSION }}
       - name: Install dependencies
-        run: python -m pip install --upgrade nox pdm==2.26.2
+        run: python -m pip install --upgrade nox pdm==2.26.4
       - name: Generate Dockerfile
         run: nox -vs generate_dockerfile
       - name: Set up QEMU
@@ -178,7 +178,7 @@ jobs:
         run: |
           sudo apt-get -y update
           sudo apt-get -y install patchelf scons
-          python -m pip install --upgrade nox pdm==2.26.2
+          python -m pip install --upgrade nox pdm==2.26.4
           git config --global --add safe.directory '*'
       - name: Bundle the distribution
         id: bundle
@@ -217,7 +217,7 @@ jobs:
         with:
           python-version: ${{ env.PYTHON_DEFAULT_VERSION }}
       - name: Install dependencies
-        run: python -m pip install --upgrade nox pdm==2.26.2
+        run: python -m pip install --upgrade nox pdm==2.26.4
       - name: Bundle the distribution
         id: bundle
         shell: bash
@@ -256,6 +256,6 @@ jobs:
         run: |
           sudo apt-get update -y
           sudo apt-get install -y graphviz plantuml
-          python -m pip install --upgrade nox pdm==2.26.2
+          python -m pip install --upgrade nox pdm==2.26.4
       - name: Build the docs
         run: nox --non-interactive -vs doc
diff --git a/b2/_internal/_cli/autocomplete_install.py b/b2/_internal/_cli/autocomplete_install.py
index dcd631ea4..57f6a28a8 100644
--- a/b2/_internal/_cli/autocomplete_install.py
+++ b/b2/_internal/_cli/autocomplete_install.py
@@ -25,7 +25,8 @@
 from shlex import quote
 
 import argcomplete
-from class_registry import ClassRegistry, RegistryKeyError
+
+from b2._internal.class_registry import ClassRegistry, RegistryKeyError
 
 logger = logging.getLogger(__name__)
 
diff --git a/b2/_internal/class_registry.py b/b2/_internal/class_registry.py
new file mode 100644
index 000000000..80754c981
--- /dev/null
+++ b/b2/_internal/class_registry.py
@@ -0,0 +1,108 @@
+######################################################################
+#
+# File: b2/_internal/class_registry.py
+#
+# Copyright 2026 Backblaze Inc. All Rights Reserved.
+#
+# License https://www.backblaze.com/using_b2_code.html
+#
+######################################################################
+from __future__ import annotations
+
+from collections import OrderedDict
+from collections.abc import Callable, Hashable, Iterable, Iterator
+from typing import Any
+
+
+class RegistryKeyError(KeyError):
+    """Raised when a registry lookup fails."""
+
+
+class ClassRegistry:
+    """Registry with decorator-based class registration and instantiation."""
+
+    def __init__(self, attr_name: str | None = None, unique: bool = False) -> None:
+        self.attr_name = attr_name
+        self.unique = unique
+        self._registry: OrderedDict[Hashable, type] = OrderedDict()
+
+    def __contains__(self, key: Hashable) -> bool:
+        try:
+            self.get_class(key)
+        except RegistryKeyError:
+            return False
+        return True
+
+    def __getitem__(self, key: Hashable) -> object:
+        return self.get(key)
+
+    def __iter__(self) -> Iterator[Hashable]:
+        return self.keys()
+
+    def __len__(self) -> int:
+        return len(self._registry)
+
+    def __repr__(self) -> str:
+        return f'{type(self).__name__}(attr_name={self.attr_name!r}, unique={self.unique!r})'
+
+    def __setitem__(self, key: Hashable, class_: type) -> None:
+        self._register(key, class_)
+
+    def __delitem__(self, key: Hashable) -> None:
+        self._unregister(key)
+
+    def __missing__(self, key: Hashable) -> object:
+        raise RegistryKeyError(key)
+
+    @staticmethod
+    def create_instance(class_: type, *args: Any, **kwargs: Any) -> object:
+        return class_(*args, **kwargs)
+
+    def get_class(self, key: Hashable) -> type:
+        try:
+            return self._registry[key]
+        except KeyError:
+            return self.__missing__(key)
+
+    def get(self, key: Hashable, *args: Any, **kwargs: Any) -> object:
+        return self.create_instance(self.get_class(key), *args, **kwargs)
+
+    def items(self) -> Iterable[tuple[Hashable, type]]:
+        return self._registry.items()
+
+    def keys(self) -> Iterable[Hashable]:
+        return self._registry.keys()
+
+    def values(self) -> Iterable[type]:
+        return self._registry.values()
+
+    def register(self, key: Hashable | type) -> Callable[[type], type] | type:
+        if isinstance(key, type):
+            if not self.attr_name:
+                raise ValueError(
+                    f'Attempting to register {key.__name__} via decorator, but attr_name is not set.'
+                )
+            attr_key = getattr(key, self.attr_name)
+            self._register(attr_key, key)
+            return key
+
+        def _decorator(cls: type) -> type:
+            self._register(key, cls)
+            return cls
+
+        return _decorator
+
+    def unregister(self, key: Hashable) -> type:
+        return self._unregister(key)
+
+    def _register(self, key: Hashable, class_: type) -> None:
+        if key in ['', None]:
+            raise ValueError(
+                f'Attempting to register class {class_.__name__} with empty registry key {key!r}.'
+            )
+        if self.unique and key in self._registry:
+            raise RegistryKeyError(f'{class_.__name__} with key {key!r} is already registered.')
+        self._registry[key] = class_
+
+    def _unregister(self, key: Hashable) -> type:
+        return self._registry.pop(key) if key in self._registry else self.__missing__(key)
diff --git a/b2/_internal/console_tool.py b/b2/_internal/console_tool.py
index 1f25c0544..d14f9834f 100644
--- a/b2/_internal/console_tool.py
+++ b/b2/_internal/console_tool.py
@@ -118,7 +118,6 @@
     UnableToCreateDirectory,
 )
 from b2sdk.version import VERSION as b2sdk_version
-from class_registry import ClassRegistry
 from tabulate import tabulate
 
 from b2._internal._cli.arg_parser_types import (
@@ -163,6 +162,7 @@
 from b2._internal._cli.shell import detect_shell, resolve_short_call_name
 from b2._internal._utils.uri import B2URI, B2FileIdURI, B2URIAdapter, B2URIBase
 from b2._internal.arg_parser import B2ArgumentParser, add_normalized_argument
+from b2._internal.class_registry import ClassRegistry
 from b2._internal.json_encoder import B2CliJsonEncoder
 from b2._internal.version import VERSION
 
diff --git a/changelog.d/1081.changed.md b/changelog.d/1081.changed.md
new file mode 100644
index 000000000..58e05935f
--- /dev/null
+++ b/changelog.d/1081.changed.md
@@ -0,0 +1 @@
+Replace the `phx-class-registry` dependency with a simple in-house implementation.
diff --git a/pdm.lock b/pdm.lock
index e17962ac0..6e4773beb 100644
--- a/pdm.lock
+++ b/pdm.lock
@@ -5,7 +5,7 @@
 groups = ["default", "bundle", "doc", "format", "full", "license", "lint", "release", "test"]
 strategy = ["cross_platform", "inherit_metadata"]
 lock_version = "4.5.0"
-content_hash = "sha256:197b3857d419ecc19bf7d330c26826205b86cb153f5b838fb25d7a8144a93cac"
+content_hash = "sha256:8fd4faeaecd3d00b7066e7c0779e4fb4011256cd0da5dad1caa581e0af1f612b"
 
 [[metadata.targets]]
 requires_python = ">=3.9"
@@ -48,7 +48,7 @@ files = [
 
 [[package]]
 name = "anyio"
-version = "4.12.0"
+version = "4.12.1"
 requires_python = ">=3.9"
 summary = "High-level concurrency and networking framework on top of asyncio or Trio"
 groups = ["doc"]
@@ -58,8 +58,8 @@ dependencies = [
     "typing-extensions>=4.5; python_version < \"3.13\"",
 ]
 files = [
-    {file = "anyio-4.12.0-py3-none-any.whl", hash = "sha256:dad2376a628f98eeca4881fc56cd06affd18f659b17a747d3ff0307ced94b1bb"},
-    {file = "anyio-4.12.0.tar.gz", hash = "sha256:73c693b567b0c55130c104d0b43a9baf3aa6a31fc6110116509f27bf75e21ec0"},
+    {file = "anyio-4.12.1-py3-none-any.whl", hash = "sha256:d405828884fc140aa80a3c667b8beed277f1dfedec42ba031bd6ac3db606ab6c"},
+    {file = "anyio-4.12.1.tar.gz", hash = "sha256:41cfcc3a4c85d3f05c932da7c26d0201ac36f72abd4435ba90d0464a3ffed703"},
 ]
 
 [[package]]
@@ -123,13 +123,13 @@ files = [
 
 [[package]]
 name = "certifi"
-version = "2025.11.12"
+version = "2026.1.4"
 requires_python = ">=3.7"
 summary = "Python package for providing Mozilla's CA Bundle."
 groups = ["default", "doc"]
 files = [
-    {file = "certifi-2025.11.12-py3-none-any.whl", hash = "sha256:97de8790030bbd5c2d96b7ec782fc2f7820ef8dba6db909ccf95449f2d062d4b"},
-    {file = "certifi-2025.11.12.tar.gz", hash = "sha256:d8ab5478f2ecd78af242878415affce761ca6bc54a22a27e026d7c25357c3316"},
+    {file = "certifi-2026.1.4-py3-none-any.whl", hash = "sha256:9943707519e4add1115f44c2bc244f782c0249876bf51b6599fee1ffbedd685c"},
+    {file = "certifi-2026.1.4.tar.gz", hash = "sha256:ac726dd470482006e014ad384921ed6438c457018f4b3d204aea4281258b2120"},
 ]
 
 [[package]]
@@ -518,18 +518,17 @@ files = [
 
 [[package]]
 name = "importlib-metadata"
-version = "8.7.0"
+version = "8.7.1"
 requires_python = ">=3.9"
 summary = "Read metadata from Python packages"
 groups = ["bundle", "doc"]
 marker = "python_version < \"3.10\""
 dependencies = [
-    "typing-extensions>=3.6.4; python_version < \"3.8\"",
     "zipp>=3.20",
 ]
 files = [
-    {file = "importlib_metadata-8.7.0-py3-none-any.whl", hash = "sha256:e5dd1551894c77868a30651cef00984d50e1002d06942a7101d34870c5f02afd"},
-    {file = "importlib_metadata-8.7.0.tar.gz", hash = "sha256:d13b81ad223b890aa16c5471f2ac3056cf76c5f10f82d6f9292f0b415f389000"},
+    {file = "importlib_metadata-8.7.1-py3-none-any.whl", hash = "sha256:5a1f80bf1daa489495071efbb095d75a634cf28a8bc299581244063b53176151"},
+    {file = "importlib_metadata-8.7.1.tar.gz", hash = "sha256:49fef1ae6440c182052f407c8d34a68f72efc36db9ca90dc0113398f2fdde8bb"},
 ]
 
 [[package]]
@@ -781,17 +780,6 @@ files = [
     {file = "pexpect-4.9.0.tar.gz", hash = "sha256:ee7d41123f3c9911050ea2c2dac107568dc43b2d3b0c7557a33212c398ead30f"},
 ]
 
-[[package]]
-name = "phx-class-registry"
-version = "4.0.6"
-requires_python = ">=3"
-summary = "Factory+Registry pattern for Python classes"
-groups = ["default"]
-files = [
-    {file = "phx-class-registry-4.0.6.tar.gz", hash = "sha256:66e9818de0a9d62e8cfe311587fcd3853ba941b71c11a7a73e5808d6550db125"},
-    {file = "phx_class_registry-4.0.6-py3-none-any.whl", hash = "sha256:90f8c44b9840ac1cb350876157669bf0d1f9d3be614a4f21d739a219a0640601"},
-]
-
 [[package]]
 name = "pip"
 version = "25.3"
@@ -1087,7 +1075,7 @@ files = [
 
 [[package]]
 name = "pyinstaller-hooks-contrib"
-version = "2025.10"
+version = "2025.11"
 requires_python = ">=3.8"
 summary = "Community maintained hooks for PyInstaller"
 groups = ["bundle"]
@@ -1097,8 +1085,8 @@ dependencies = [
     "setuptools>=42.0.0",
 ]
 files = [
-    {file = "pyinstaller_hooks_contrib-2025.10-py3-none-any.whl", hash = "sha256:aa7a378518772846221f63a84d6306d9827299323243db890851474dfd1231a9"},
-    {file = "pyinstaller_hooks_contrib-2025.10.tar.gz", hash = "sha256:a1a737e5c0dccf1cf6f19a25e2efd109b9fec9ddd625f97f553dac16ee884881"},
+    {file = "pyinstaller_hooks_contrib-2025.11-py3-none-any.whl", hash = "sha256:777e163e2942474aa41a8e6d31ac1635292d63422c3646c176d584d04d971c34"},
+    {file = "pyinstaller_hooks_contrib-2025.11.tar.gz", hash = "sha256:dfe18632e06655fa88d218e0d768fd753e1886465c12a6d4bce04f1aaeec917d"},
 ]
 
 [[package]]
@@ -1290,7 +1278,7 @@ name = "setuptools"
 version = "79.0.1"
 requires_python = ">=3.9"
 summary = "Easily download, build, install, upgrade, and uninstall Python packages"
-groups = ["default", "bundle", "lint"]
+groups = ["bundle", "lint"]
 files = [
     {file = "setuptools-79.0.1-py3-none-any.whl", hash = "sha256:e147c0549f27767ba362f9da434eab9c5dc0045d5304feb602a0af001089fc51"},
     {file = "setuptools-79.0.1.tar.gz", hash = "sha256:128ce7b8f33c3079fd1b067ecbb4051a66e8526e7b65f6cec075dfc650ddfa88"},
@@ -1614,54 +1602,59 @@ files = [
 
 [[package]]
 name = "tomli"
-version = "2.3.0"
+version = "2.4.0"
 requires_python = ">=3.8"
 summary = "A lil' TOML parser"
 groups = ["doc", "license", "lint", "release", "test"]
 marker = "python_version < \"3.11\""
 files = [
-    {file = "tomli-2.3.0-cp311-cp311-macosx_10_9_x86_64.whl", hash = "sha256:88bd15eb972f3664f5ed4b57c1634a97153b4bac4479dcb6a495f41921eb7f45"},
-    {file = "tomli-2.3.0-cp311-cp311-macosx_11_0_arm64.whl", hash = "sha256:883b1c0d6398a6a9d29b508c331fa56adbcdff647f6ace4dfca0f50e90dfd0ba"},
-    {file = "tomli-2.3.0-cp311-cp311-manylinux2014_aarch64.manylinux_2_17_aarch64.manylinux_2_28_aarch64.whl", hash = "sha256:d1381caf13ab9f300e30dd8feadb3de072aeb86f1d34a8569453ff32a7dea4bf"},
-    {file = "tomli-2.3.0-cp311-cp311-manylinux2014_x86_64.manylinux_2_17_x86_64.manylinux_2_28_x86_64.whl", hash = "sha256:a0e285d2649b78c0d9027570d4da3425bdb49830a6156121360b3f8511ea3441"},
-    {file = "tomli-2.3.0-cp311-cp311-musllinux_1_2_aarch64.whl", hash = "sha256:0a154a9ae14bfcf5d8917a59b51ffd5a3ac1fd149b71b47a3a104ca4edcfa845"},
-    {file = "tomli-2.3.0-cp311-cp311-musllinux_1_2_x86_64.whl", hash = "sha256:74bf8464ff93e413514fefd2be591c3b0b23231a77f901db1eb30d6f712fc42c"},
-    {file = "tomli-2.3.0-cp311-cp311-win32.whl", hash = "sha256:00b5f5d95bbfc7d12f91ad8c593a1659b6387b43f054104cda404be6bda62456"},
-    {file = "tomli-2.3.0-cp311-cp311-win_amd64.whl", hash = "sha256:4dc4ce8483a5d429ab602f111a93a6ab1ed425eae3122032db7e9acf449451be"},
-    {file = "tomli-2.3.0-cp312-cp312-macosx_10_13_x86_64.whl", hash = "sha256:d7d86942e56ded512a594786a5ba0a5e521d02529b3826e7761a05138341a2ac"},
-    {file = "tomli-2.3.0-cp312-cp312-macosx_11_0_arm64.whl", hash = "sha256:73ee0b47d4dad1c5e996e3cd33b8a76a50167ae5f96a2607cbe8cc773506ab22"},
-    {file = "tomli-2.3.0-cp312-cp312-manylinux2014_aarch64.manylinux_2_17_aarch64.manylinux_2_28_aarch64.whl", hash = "sha256:792262b94d5d0a466afb5bc63c7daa9d75520110971ee269152083270998316f"},
-    {file = "tomli-2.3.0-cp312-cp312-manylinux2014_x86_64.manylinux_2_17_x86_64.manylinux_2_28_x86_64.whl", hash = "sha256:4f195fe57ecceac95a66a75ac24d9d5fbc98ef0962e09b2eddec5d39375aae52"},
-    {file = "tomli-2.3.0-cp312-cp312-musllinux_1_2_aarch64.whl", hash = "sha256:e31d432427dcbf4d86958c184b9bfd1e96b5b71f8eb17e6d02531f434fd335b8"},
-    {file = "tomli-2.3.0-cp312-cp312-musllinux_1_2_x86_64.whl", hash = "sha256:7b0882799624980785240ab732537fcfc372601015c00f7fc367c55308c186f6"},
-    {file = "tomli-2.3.0-cp312-cp312-win32.whl", hash = "sha256:ff72b71b5d10d22ecb084d345fc26f42b5143c5533db5e2eaba7d2d335358876"},
-    {file = "tomli-2.3.0-cp312-cp312-win_amd64.whl", hash = "sha256:1cb4ed918939151a03f33d4242ccd0aa5f11b3547d0cf30f7c74a408a5b99878"},
-    {file = "tomli-2.3.0-cp313-cp313-macosx_10_13_x86_64.whl", hash = "sha256:5192f562738228945d7b13d4930baffda67b69425a7f0da96d360b0a3888136b"},
-    {file = "tomli-2.3.0-cp313-cp313-macosx_11_0_arm64.whl", hash = "sha256:be71c93a63d738597996be9528f4abe628d1adf5e6eb11607bc8fe1a510b5dae"},
-    {file = "tomli-2.3.0-cp313-cp313-manylinux2014_aarch64.manylinux_2_17_aarch64.manylinux_2_28_aarch64.whl", hash = "sha256:c4665508bcbac83a31ff8ab08f424b665200c0e1e645d2bd9ab3d3e557b6185b"},
-    {file = "tomli-2.3.0-cp313-cp313-manylinux2014_x86_64.manylinux_2_17_x86_64.manylinux_2_28_x86_64.whl", hash = "sha256:4021923f97266babc6ccab9f5068642a0095faa0a51a246a6a02fccbb3514eaf"},
-    {file = "tomli-2.3.0-cp313-cp313-musllinux_1_2_aarch64.whl", hash = "sha256:a4ea38c40145a357d513bffad0ed869f13c1773716cf71ccaa83b0fa0cc4e42f"},
-    {file = "tomli-2.3.0-cp313-cp313-musllinux_1_2_x86_64.whl", hash = "sha256:ad805ea85eda330dbad64c7ea7a4556259665bdf9d2672f5dccc740eb9d3ca05"},
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+    {file = "tomli-2.4.0.tar.gz", hash = "sha256:aa89c3f6c277dd275d8e243ad24f3b5e701491a860d5121f2cdd399fbb31fc9c"},
 ]
 
 [[package]]
@@ -1735,18 +1728,18 @@ files = [
 
 [[package]]
 name = "urllib3"
-version = "2.6.2"
+version = "2.6.3"
 requires_python = ">=3.9"
 summary = "HTTP library with thread-safe connection pooling, file post, and more."
 groups = ["default", "doc"]
 files = [
-    {file = "urllib3-2.6.2-py3-none-any.whl", hash = "sha256:ec21cddfe7724fc7cb4ba4bea7aa8e2ef36f607a4bab81aa6ce42a13dc3f03dd"},
-    {file = "urllib3-2.6.2.tar.gz", hash = "sha256:016f9c98bb7e98085cb2b4b17b87d2c702975664e4f060c6532e64d1c1a5e797"},
+    {file = "urllib3-2.6.3-py3-none-any.whl", hash = "sha256:bf272323e553dfb2e87d9bfd225ca7b0f467b919d7bbd355436d3fd37cb0acd4"},
+    {file = "urllib3-2.6.3.tar.gz", hash = "sha256:1b62b6884944a57dbe321509ab94fd4d3b307075e0c2eae991ac71ee15ad38ed"},
 ]
 
 [[package]]
 name = "uvicorn"
-version = "0.38.0"
+version = "0.39.0"
 requires_python = ">=3.9"
 summary = "The lightning-fast ASGI server."
 groups = ["doc"]
@@ -1756,8 +1749,8 @@ dependencies = [
     "typing-extensions>=4.0; python_version < \"3.11\"",
 ]
 files = [
-    {file = "uvicorn-0.38.0-py3-none-any.whl", hash = "sha256:48c0afd214ceb59340075b4a052ea1ee91c16fbc2a9b1469cca0e54566977b02"},
-    {file = "uvicorn-0.38.0.tar.gz", hash = "sha256:fd97093bdd120a2609fc0d3afe931d4d4ad688b6e75f0f929fde1bc36fe0e91d"},
+    {file = "uvicorn-0.39.0-py3-none-any.whl", hash = "sha256:7beec21bd2693562b386285b188a7963b06853c0d006302b3e4cfed950c9929a"},
+    {file = "uvicorn-0.39.0.tar.gz", hash = "sha256:610512b19baa93423d2892d7823741f6d27717b642c8964000d7194dded19302"},
 ]
 
 [[package]]
diff --git a/pyproject.toml b/pyproject.toml
index 7eec988d9..14e72d23a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -28,12 +28,10 @@ dependencies = [
     "b2sdk>=2.10.2,<3",
     "docutils>=0.18.1,<0.22",
     "idna~=3.4; platform_system == 'Java'",
-    "phx-class-registry>=4.0,<5",
     "rst2ansi==0.1.5",
     "tabulate==0.9.0",
     "tqdm>=4.65.0,<5",
     "platformdirs>=3.11.0,<5",
-    "setuptools>=60,<80; python_version < '3.10'",  # required by phx-class-registry<4.1
 ]
 
 [project.optional-dependencies]
diff --git a/test/unit/test_class_registry.py b/test/unit/test_class_registry.py
new file mode 100644
index 000000000..d8b2e9453
--- /dev/null
+++ b/test/unit/test_class_registry.py
@@ -0,0 +1,103 @@
+######################################################################
+#
+# File: test/unit/test_class_registry.py
+#
+# Copyright 2026 Backblaze Inc. All Rights Reserved.
+#
+# License https://www.backblaze.com/using_b2_code.html
+#
+######################################################################
+
+import pytest
+
+from b2._internal.class_registry import ClassRegistry, RegistryKeyError
+
+
+def test_register_with_key_and_get_instance():
+    registry = ClassRegistry()
+
+    @registry.register('shell')
+    class ShellInstaller:
+        def __init__(self, prog: str) -> None:
+            self.prog = prog
+
+    instance = registry.get('shell', 'b2')
+
+    assert isinstance(instance, ShellInstaller)
+    assert instance.prog == 'b2'
+
+    instance_kwargs = registry.get('shell', prog='b2-kw')
+    assert isinstance(instance_kwargs, ShellInstaller)
+    assert instance_kwargs.prog == 'b2-kw'
+
+
+def test_register_with_attr_name():
+    registry = ClassRegistry(attr_name='COMMAND_NAME')
+
+    @registry.register
+    class ListBuckets:
+        COMMAND_NAME = 'list-buckets'
+
+    assert 'list-buckets' in registry
+    assert isinstance(registry.get('list-buckets'), ListBuckets)
+
+    with pytest.raises(AttributeError):
+
+        @registry.register
+        class MissingKey:
+            pass
+
+
+def test_register_requires_key_without_attr_name():
+    registry = ClassRegistry()
+
+    with pytest.raises(ValueError):
+
+        @registry.register
+        class MissingKey:
+            pass
+
+
+def test_duplicate_key_overrides():
+    registry = ClassRegistry()
+
+    @registry.register('dup')
+    class First:
+        pass
+
+    @registry.register('dup')
+    class Second:
+        pass
+
+    assert registry.get('dup').__class__ is Second
+
+
+def test_duplicate_key_raises_when_unique():
+    registry = ClassRegistry(unique=True)
+
+    @registry.register('dup')
+    class First:
+        pass
+
+    with pytest.raises(RegistryKeyError):
+
+        @registry.register('dup')
+        class Second:
+            pass
+
+
+def test_missing_key_raises_registry_key_error():
+    registry = ClassRegistry()
+
+    with pytest.raises(RegistryKeyError):
+        registry.get('missing')
+
+
+def test_empty_key_is_rejected():
+    registry = ClassRegistry()
+
+    with pytest.raises(ValueError):
+
+        @registry.register('')
+        class EmptyKey:
+            pass