diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 5a9f67b..fbb0be5 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -110,7 +110,7 @@ jobs:
       - name: Install macOS build prerequisites
         if: runner.os == 'macOS'
         run: |
-          brew install automake libdeflate
+          ./ci/osx-deps
 
       - name: Install
         run: |
@@ -216,7 +216,7 @@ jobs:
 
       - name: Test
         run: |
-          pytest --cov cyvcf2 --cov-report term-missing
+          pytest --import-mode importlib --cov cyvcf2 --cov-report term-missing
 
       - name: Upload sdist tarball
         if: runner.os == 'Linux'