diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index f25e387..01b27b5 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -4,7 +4,7 @@ jobs:
   test:
     strategy:
       matrix:
-        os: [ubuntu-20.04]
+        os: [ubuntu-18.04]
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.os }}
     steps: