diff --git a/.github/workflows/python-package.yml b/.github/workflows/python-package.yml
index 7f53be8..f90f878 100644
--- a/.github/workflows/python-package.yml
+++ b/.github/workflows/python-package.yml
@@ -43,9 +43,14 @@ jobs:
           poetry ruff planetarium/.
           poetry mypy planetarium/.
 
+      - name: Setup apptainer
+        uses: eWaterCycle/setup-apptainer@v2.0.0
+
       - name: test
         run: |
           source .venv/bin/activate
+          apptainer pull fast-downward.sif docker://aibasel/downward:latest
+          export DOWNWARD=$(pwd)/fast-downward.sif
           mkdir tmp
           curl -o tmp/VAL.zip https://dev.azure.com/schlumberger/4e6bcb11-cd68-40fe-98a2-e3777bfec0a6/_apis/build/builds/77/artifacts?artifactName=linux64\&api-version=7.1\&%24format=zip
           unzip tmp/VAL.zip -d tmp/
diff --git a/planetarium/evaluate.py b/planetarium/evaluate.py
index 53cb1c9..a79a3aa 100644
--- a/planetarium/evaluate.py
+++ b/planetarium/evaluate.py
@@ -9,6 +9,7 @@
 
 
 VALIDATE = os.getenv("VALIDATE", "Validate")
+DOWNWARD = os.getenv("DOWNWARD", "downward")
 DOMAINS = dict()
 
 # load domains
@@ -24,6 +25,7 @@ def evaluate(
     is_placeholder: bool = False,
     check_solveable: bool = True,
     val: str = VALIDATE,
+    fast_downward: str = DOWNWARD,
     **downward_args,
 ) -> tuple[bool, bool, bool]:
     """Evaluate two PDDL problem descriptions for equivalence.
@@ -67,6 +69,7 @@ def evaluate(
                 plan_str, _ = downward.plan(
                     domain_str,
                     clean_pddl_str,
+                    downward=fast_downward,
                     **downward_args,
                 )
             except: