diff --git a/.github/workflows/R-CMD-check.yaml b/.github/workflows/R-CMD-check.yaml
index cfb3c6bf..eca3c426 100644
--- a/.github/workflows/R-CMD-check.yaml
+++ b/.github/workflows/R-CMD-check.yaml
@@ -29,7 +29,7 @@ jobs:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2
 
       - uses: r-lib/actions/setup-r@master
         with:
@@ -46,7 +46,7 @@ jobs:
 
       - name: Cache R packages
         if: runner.os != 'Windows'
-        uses: actions/cache@v1
+        uses: actions/cache@f5ce41475b483ad7581884324a6eca9f48f8dcc7 # v1
         with:
           path: ${{ env.R_LIBS_USER }}
           key: ${{ runner.os }}-${{ hashFiles('.github/R-version') }}-1-${{ hashFiles('.github/depends.Rds') }}
@@ -87,7 +87,7 @@ jobs:
 
       - name: Upload check results
         if: failure()
-        uses: actions/upload-artifact@master
+        uses: actions/upload-artifact@0c366cb4fc8897159c94880f94b55bc716ad6a66 # master
         with:
           name: ${{ runner.os }}-r${{ matrix.config.r }}-results
           path: check