diff --git a/.github/workflows/run-tests.yaml b/.github/workflows/run-tests.yaml
index 82c69a1..561b9ff 100644
--- a/.github/workflows/run-tests.yaml
+++ b/.github/workflows/run-tests.yaml
@@ -72,6 +72,10 @@ jobs:
 
   test-high-level:
     runs-on: ubuntu-latest
+    env:
+      OMP_NUM_THREADS: '1'
+      MKL_NUM_THREADS: '1'
+      OPENBLAS_NUM_THREADS: '1'
     steps:
     - name: Check out repository
       uses: actions/checkout@v2
@@ -81,8 +85,9 @@ jobs:
         python-version: '3.10'
     - name: Install high-level dependencies
       run: |
+        pip install "numba>=0.62.0"
         pip install -r tests/requirements-core.txt
-        pip install numba
+        pip install --upgrade numpy
     - name: Run high-level tests
       run: |
         python -X faulthandler -m unittest discover tests/high_level
diff --git a/bm25s/high_level.py b/bm25s/high_level.py
index e179738..69b2208 100644
--- a/bm25s/high_level.py
+++ b/bm25s/high_level.py
@@ -73,8 +73,8 @@ def __init__(
             return_as="tuple",
         )
 
-        # compile and index
-        self.retriever.compile(activate_numba=True, warmup=True)
+        # compile and index (warmup=False to avoid segfaults in some CI environments)
+        self.retriever.compile(activate_numba=True, warmup=False)
         
         create_empty_token = True
         # If the corpus is empty or has no tokens, we can't create an empty token