diff --git a/.github/workflows/unit_tests.yml b/.github/workflows/unit_tests.yml
index 7163bc88..c262c91c 100644
--- a/.github/workflows/unit_tests.yml
+++ b/.github/workflows/unit_tests.yml
@@ -30,6 +30,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install flake8 pytest
+        pip install hnn_core
 
     - name: Install HNN
       run: |