diff --git a/.github/workflows/R-CMD-check.yaml b/.github/workflows/R-CMD-check.yaml
index ac091f3..701f30e 100644
--- a/.github/workflows/R-CMD-check.yaml
+++ b/.github/workflows/R-CMD-check.yaml
@@ -2,9 +2,9 @@ name: R-CMD-check
 
 on:
   push:
-    branches: [main, master]
+    branches: main
   pull_request:
-    branches: [main, master]
+    branches: main
 
 jobs:
   R-CMD-check:
@@ -16,8 +16,11 @@ jobs:
       fail-fast: false
       matrix:
         config:
+          - {os: macos-latest,   r: 'release'}
           - {os: windows-latest, r: 'release'}
-
+          - {os: ubuntu-latest,   r: 'devel', http-user-agent: 'release'}
+          - {os: ubuntu-latest,   r: 'release'}
+          - {os: ubuntu-latest,   r: 'oldrel-1'}
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
       R_KEEP_PKG_SOURCE: yes
diff --git a/.github/workflows/lint.yaml b/.github/workflows/lint.yaml
index 8ed0c6e..5a281e5 100644
--- a/.github/workflows/lint.yaml
+++ b/.github/workflows/lint.yaml
@@ -2,9 +2,9 @@ name: lint
 
 on:
   push:
-    branches: [main, master]
+    branches: main
   pull_request:
-    branches: [main, master]
+    branches: main
 
 jobs:
   lint:
diff --git a/.github/workflows/pkgdown.yaml b/.github/workflows/pkgdown.yaml
index fb6645f..70614cd 100644
--- a/.github/workflows/pkgdown.yaml
+++ b/.github/workflows/pkgdown.yaml
@@ -2,9 +2,9 @@
 # Need help debugging build failures? Start at https://github.com/r-lib/actions#where-to-find-help
 on:
   push:
-    branches: [main, master]
+    branches: main
   pull_request:
-    branches: [main, master]
+    branches: main
   release:
     types: [published]
   workflow_dispatch: