diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index f554154..f42c54c 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -45,6 +45,8 @@ jobs:
     name: test-${{ matrix.tox-env }} (Python${{ matrix.python-version }})
     needs: lint
     runs-on: ubuntu-latest
+    env:
+      ESMF_VERSION: "v8.5.0"
     strategy:
       matrix:
         include:
@@ -58,6 +60,17 @@ jobs:
             python-version: "3.11"
     steps:
       - uses: actions/checkout@v4.1.1
+      - name: Install NetCDF
+        run: |
+          sudo apt-get -y update
+          sudo apt install libnetcdf-dev libnetcdff-dev
+      - name: Install ESMF
+        uses: esmf-org/install-esmf-action@v1
+        env:
+          ESMF_NETCDF: nc-config
+        with:
+          cache: true
+          version: ${{ env.ESMF_VERSION }}
       - name: Set up Python${{ matrix.python-version }}
         uses: actions/setup-python@v4.7.1
         with:
@@ -68,11 +81,12 @@ jobs:
       - name: Test with tox
         run: |
           tox -e ${{ matrix.tox-env }}
-#        env:
-#          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-#          COVERALLS_FLAG_NAME: run-${{ matrix.tox-env }}
-#          COVERALLS_PARALLEL: true
-#          COVERALLS_SERVICE_NAME: github
+        env:
+          ESMF_VERSION: ${{ env.ESMF_VERSION }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          COVERALLS_FLAG_NAME: run-${{ matrix.tox-env }}
+          COVERALLS_PARALLEL: true
+          COVERALLS_SERVICE_NAME: github
 
 #  test-conda:
 #    name: Test with Python${{ matrix.python-version }} (Anaconda)
diff --git a/tox.ini b/tox.ini
index b963aae..9d0d230 100644
--- a/tox.ini
+++ b/tox.ini
@@ -39,12 +39,15 @@ setenv =
 passenv =
     CI
     COVERALLS_*
+    ESMFMKFILE
+    ESMF_VERSION
     GITHUB_*
 extras =
     dev
 download = True
 install_command = python -m pip install --no-user {opts} {packages}
 deps =
+    git+https://github.com/esmf-org/esmf.git@{env:ESMF_VERSION}\#subdirectory=src/addon/esmpy
 ; If you want to make tox run the tests with the same versions, create a
 ; requirements.txt with the pinned versions and uncomment the following line:
 ;     -r{toxinidir}/requirements.txt