diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index eb74980..0da3512 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -28,24 +28,31 @@ jobs:
           echo "    pre-commit run --all-files --hook-stage=manual"
 
   test:
-    name: Run tests on ${{ matrix.os }}
+    name: Run tests on ${{ matrix.os }} python-${{ matrix.python-version }}
     runs-on: ${{ matrix.os }}
 
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
+        python-version:
+          - '3.9'
+          - '3.10'
+          - '3.11'
+          - '3.12'
+          - '3.13'
+          - 'pypy3.9'
+          - 'pypy3.10'
+          - 'pypy3.11'
     defaults:
       run:
         shell: bash -l {0}
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
-      - name: Install mamba
-        uses: mamba-org/setup-micromamba@v1
+      - uses: actions/setup-node@v4
+      - uses: actions/setup-python@v5
         with:
-          environment-file: environment-dev.yml
-          environment-name: pycrdt-websocket
-          extra-specs: python=${{ matrix.python-version }}
+          python-version: ${{ matrix.python-version }}
       - name: Ensure pip >= v25.1
         run: python -m pip install "pip >= 25.1"
       - name: Install dependencies
diff --git a/environment-dev.yml b/environment-dev.yml
deleted file mode 100644
index b39383f..0000000
--- a/environment-dev.yml
+++ /dev/null
@@ -1,6 +0,0 @@
-name: pycrdt-websocket
-channels:
-  - conda-forge
-dependencies:
-  - pip
-  - nodejs
diff --git a/tests/utils.py b/tests/utils.py
index 958b078..182491a 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from anyio import Lock, connect_tcp, create_memory_object_stream
 
 from pycrdt import Array, Doc
@@ -62,7 +64,7 @@ async def recv(self) -> bytes:
 
 
 class ClientWebsocket:
-    def __init__(self, server_websocket: "ServerWebsocket"):
+    def __init__(self, server_websocket: ServerWebsocket):
         self.server_websocket = server_websocket
         self.send_stream, self.receive_stream = create_memory_object_stream[bytes](65536)