diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 9459331..9f8ef97 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -12,10 +12,10 @@ jobs:
       packages: write
     steps:
     - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
 
     - name: Setup Spack
-      uses: spack/setup-spack@v2
+      uses: spack/setup-spack@e29ea3dfd0fe3d8a5c6e0050835b436b742a1951
 
     - name: Find compilers
       run: spack -e . compiler find --mixed-toolchain