diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index baa89125..acba0fd2 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -78,10 +78,15 @@ jobs:
       with:
         python-version: ${{ matrix.python-version }}
 
+    - name: Pre-install dependencies
+      run: |
+        pip install -vU pip
+        pip install -vU setuptools wheel Cython scipy 'numpy<2'  # for corrfunc, classy
+        pip install -vU --no-build-isolation corrfunc classy
+
     - name: Install package from source
       if: ${{ env.PUBLISH != 'true' }}
       run: |
-        pip install -U pip
         pip install -vU .[test]
         make -C pipe_asdf