diff --git a/.github/workflows/R-CMD-check.yaml b/.github/workflows/R-CMD-check.yaml
index 55c5533..afd704f 100644
--- a/.github/workflows/R-CMD-check.yaml
+++ b/.github/workflows/R-CMD-check.yaml
@@ -29,9 +29,9 @@ jobs:
           - {os: windows-latest, r: '3.6'}
 
           # Use older ubuntu to maximise backward compatibility
-          - {os: ubuntu-18.04,   r: 'devel', http-user-agent: 'release'}
-          - {os: ubuntu-18.04,   r: 'release'}
-          - {os: ubuntu-18.04,   r: 'oldrel-1'}
+          - {os: ubuntu-20.04,   r: 'devel', http-user-agent: 'release'}
+          - {os: ubuntu-20.04,   r: 'release'}
+          - {os: ubuntu-20.04,   r: 'oldrel-1'}
 
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}