diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9062a1d..9124a94 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,13 +12,13 @@ jobs:
     timeout-minutes: 10
     strategy:
       matrix:
-        os: [windows-latest]
+        os: [ubuntu-latest]
     steps:
     - uses: actions/checkout@v2
     - name: Setup .NET
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 5.0.x
+        dotnet-version: 3.1.x
     - name: Build
       run: dotnet build -c Release
     - name: Test