diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 2fccc47..7daed04 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -97,7 +97,7 @@ jobs:
   oldest-supported-installer:
     strategy:
         matrix:
-          os: [ubuntu-latest, macos-latest]
+          os: [ubuntu-latest, macos-10.15]
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2.3.5