diff --git a/.github/workflows/codecov.yml b/.github/workflows/codecov.yml
index afd23d94..f9d7b682 100644
--- a/.github/workflows/codecov.yml
+++ b/.github/workflows/codecov.yml
@@ -51,7 +51,7 @@ jobs:
         python -m pip install --upgrade pip
         python -m pip install ninja meson meson-python>=0.15.0 numpy==1.26.4 Cython>=0.29 spin pybind11
         python -m pip install tifffile>=2024.7.2 pyvips>=2.2.3 tqdm>=2.66.4 pillow>=10.3.0 openslide-python>=1.3.1
-        python -m pip install opencv-python-headless>=4.9.0.80 shapely>=2.0.4 pybind11>=2.8.0 pydantic coverage pytest psutil darwin-py
+        python -m pip install opencv-python-headless>=4.9.0.80 shapely>=2.0.4 pybind11>=2.8.0 pydantic coverage pytest psutil darwin-py mocker
         echo "Python executable: $(which python)"
         echo "Python version: $(python --version)"
         echo "Current directory: $PWD"