diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index f448df5..3519301 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -12,7 +12,7 @@ jobs:
   build:
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-20.04, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
     timeout-minutes: 360
     steps: