diff --git a/.github/workflows/R-CMD-check.yaml b/.github/workflows/R-CMD-check.yaml
index 9d9bd1233..5fabb5e3f 100644
--- a/.github/workflows/R-CMD-check.yaml
+++ b/.github/workflows/R-CMD-check.yaml
@@ -140,7 +140,6 @@ jobs:
         config:
           - {os: windows-latest, r: 'release'}
           # Use 3.6 to trigger usage of RTools35
-          - {os: windows-latest, r: '3.6'}
 
     steps:
       - uses: actions/checkout@v4
@@ -199,7 +198,6 @@ jobs:
           # End custom: R 3.5
 
           # Begin custom: R 3.4
-          - {os: ubuntu-22.04,   r: 'oldrel-4'}
           # End custom: R 3.4
 
           # Begin custom: matrix elements