diff --git a/.github/workflows/R-CMD-check-wsl.yaml b/.github/workflows/R-CMD-check-wsl.yaml
index fab258cb0..50ecb1f13 100644
--- a/.github/workflows/R-CMD-check-wsl.yaml
+++ b/.github/workflows/R-CMD-check-wsl.yaml
@@ -15,7 +15,7 @@ name: Unit tests - WSL Backend
 jobs:
   WSL-R-CMD-check:
     if: "! contains(github.event.head_commit.message, '[ci skip]')"
-    runs-on: windows-latest
+    runs-on: windows-2019
 
     name: windows-latest-WSLv1
 
diff --git a/.github/workflows/R-CMD-check.yaml b/.github/workflows/R-CMD-check.yaml
index eec33fb20..a793ae11f 100644
--- a/.github/workflows/R-CMD-check.yaml
+++ b/.github/workflows/R-CMD-check.yaml
@@ -25,9 +25,9 @@ jobs:
         config:
           - {os: macOS-latest, r: 'devel', rtools: ''}
           - {os: macOS-latest, r: 'release', rtools: ''}
-          - {os: windows-latest, r: 'devel', rtools: '42'}
-          - {os: windows-latest, r: 'release', rtools: '42'}
-          - {os: windows-latest, r: 'oldrel', rtools: '40'}
+          - {os: windows-2019, r: 'devel', rtools: '42'}
+          - {os: windows-2019, r: 'release', rtools: '42'}
+          - {os: windows-2019, r: 'oldrel', rtools: '40'}
           - {os: ubuntu-20.04, r: 'devel', rtools: ''}
           - {os: ubuntu-20.04, r: 'release', rtools: ''}
           - {os: ubuntu-20.04, r: 'oldrel', rtools: ''}
diff --git a/.github/workflows/cmdstan-tarball-check.yaml b/.github/workflows/cmdstan-tarball-check.yaml
index f88eca741..18260766c 100644
--- a/.github/workflows/cmdstan-tarball-check.yaml
+++ b/.github/workflows/cmdstan-tarball-check.yaml
@@ -23,7 +23,7 @@ jobs:
       matrix:
         config:
           - {os: macOS-latest, r: 'release', rtools: ''}
-          - {os: windows-latest, r: 'release', rtools: '42'}
+          - {os: windows-2019, r: 'release', rtools: '42'}
           - {os: ubuntu-20.04, r: 'release', rtools: ''}
     env:
       R_REMOTES_NO_ERRORS_FROM_WARNINGS: true