diff --git a/.github/workflows/R-CMD-check.yaml b/.github/workflows/R-CMD-check.yaml
index 1455390..a60b16a 100644
--- a/.github/workflows/R-CMD-check.yaml
+++ b/.github/workflows/R-CMD-check.yaml
@@ -29,12 +29,12 @@ 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-18.04,   r: 'oldrel-2'}
-          - {os: ubuntu-18.04,   r: 'oldrel-3'}
-          - {os: ubuntu-18.04,   r: 'oldrel-4'}
+          - {os: ubuntu-latest,  r: 'devel', http-user-agent: 'release'}
+          - {os: ubuntu-latest,  r: 'release'}
+          - {os: ubuntu-latest,  r: 'oldrel-1'}
+          - {os: ubuntu-latest,  r: 'oldrel-2'}
+          - {os: ubuntu-latest,  r: 'oldrel-3'}
+          - {os: ubuntu-latest,  r: 'oldrel-4'}
 
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
diff --git a/.github/workflows/test-coverage.yaml b/.github/workflows/test-coverage.yaml
index 31290dd..f784598 100644
--- a/.github/workflows/test-coverage.yaml
+++ b/.github/workflows/test-coverage.yaml
@@ -18,7 +18,7 @@ jobs:
         config:
           - {os: macOS-latest,   r: 'release'}
           - {os: windows-latest, r: 'release'}
-          - {os: ubuntu-18.04,   r: 'release'}
+          - {os: ubuntu-latest,  r: 'release'}
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}