diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0b4fb74..d1a521e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -78,7 +78,7 @@ jobs:
 
   Test:
     name: Test (Elixir ${{ matrix.versions.elixir }} OTP ${{ matrix.versions.otp }})
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     strategy:
       fail-fast: false