diff --git a/.github/workflows/haskell.yml b/.github/workflows/haskell.yml
index ff3d34f..cf8b697 100644
--- a/.github/workflows/haskell.yml
+++ b/.github/workflows/haskell.yml
@@ -17,15 +17,15 @@ jobs:
     env:
       CONFIG: "--enable-tests"
     steps:
-      - uses: actions/checkout@v3
-      - uses: haskell-actions/setup@v2
+      - uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3.6.0
+      - uses: haskell-actions/setup@7909071ceec0344debcc968c6c7a96a52e8dd0d7 # v2.8.1
         id: setup-haskell-cabal
         with:
           ghc-version: ${{ matrix.ghc }}
           cabal-version: ${{ matrix.cabal }}
       - run: cabal v2-update
       - run: cabal v2-freeze $CONFIG
-      - uses: actions/cache@v3
+      - uses: actions/cache@2f8e54208210a422b2efd51efaa6bd6d7ca8920f # v3.4.3
         with:
           path: |
             ${{ steps.setup-haskell-cabal.outputs.cabal-store }}