diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index acb62f926..cc5ec9c17 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -65,6 +65,10 @@ jobs:
                       **/requirements*.txt
 
             - name: Install package test dependencies
+              # Test test will actually happened in the container, here only need to install
+              # the pytest-docker dependency.
+              # To add the dependencies to the container, we need to add them to the
+              # installation command in the `test_notebooks/conftest.py`.
               run: pip install -e .[dev]
 
             - name: Set jupyter token env
@@ -133,7 +137,7 @@ jobs:
                       **/requirements*.txt
 
             - name: Install package
-              run: pip install -e .[dev,smiles]
+              run: pip install -e .[dev,smiles,optimade]
 
             - name: Run pytest
               run: pytest -v tests --cov
diff --git a/tests_notebooks/conftest.py b/tests_notebooks/conftest.py
index 5d94186bc..ce48f233e 100644
--- a/tests_notebooks/conftest.py
+++ b/tests_notebooks/conftest.py
@@ -61,7 +61,7 @@ def notebook_service(docker_ip, docker_services, aiidalab_exec):
     aiidalab_exec("chmod -R a+rw /home/jovyan/apps/aiidalab-widgets-base", user="root")
 
     # Install AWB with extra dependencies for SmilesWidget
-    aiidalab_exec("pip install --no-cache-dir .[smiles]")
+    aiidalab_exec("pip install --no-cache-dir .[smiles, optimade]")
 
     # `port_for` takes a container port and returns the corresponding host port
     port = docker_services.port_for("aiidalab", 8888)