diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 486f3f4db..193943db9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -30,7 +30,7 @@ jobs:
         run: |
           source /var/python/3.10/virtualenv/bin/activate
           python -m pip install --upgrade pip
-          python -m pip install flepimop/gempyor_pkg/
+          python -m pip install "flepimop/gempyor_pkg[test]"
         shell: bash
       - name: Install local R packages
         run: Rscript build/local_install.R
diff --git a/flepimop/gempyor_pkg/setup.cfg b/flepimop/gempyor_pkg/setup.cfg
index ce7fd7f1b..1ad3526b2 100644
--- a/flepimop/gempyor_pkg/setup.cfg
+++ b/flepimop/gempyor_pkg/setup.cfg
@@ -31,10 +31,17 @@ install_requires =
     pyarrow
     sympy
     dask
-    pytest
     scipy
     graphviz
 
+# see https://stackoverflow.com/questions/58826164/dependencies-requirements-for-setting-up-testing-and-installing-a-python-lib
+# installed for pip install -e ".[test]"
+[options.extras_require]  
+test =
+    pytest
+    mock
+
+
 [options.entry_points]
 console_scripts =
     gempyor-outcomes = gempyor.simulate_outcome:simulate