diff --git a/.github/workflows/docs-site-checks.yml b/.github/workflows/docs-site-checks.yml
index 14cdb8f6a6..ea05d28046 100644
--- a/.github/workflows/docs-site-checks.yml
+++ b/.github/workflows/docs-site-checks.yml
@@ -27,8 +27,8 @@ jobs:
         with:
           python-version: '3.11'
 
-      - name: Install Python dependencies
-        run: python -m pip install ascii-guard pyyaml
+      - name: Install ascii-guard
+        run: python -m pip install ascii-guard==2.3.0 pyyaml==6.0.3
 
       - name: Extract skill metadata for dashboard
         run: python3 website/scripts/extract-skills.py
diff --git a/.github/workflows/nix.yml b/.github/workflows/nix.yml
index 004f8236a2..dba33bfffc 100644
--- a/.github/workflows/nix.yml
+++ b/.github/workflows/nix.yml
@@ -27,8 +27,8 @@ jobs:
     timeout-minutes: 30
     steps:
       - uses: actions/checkout@v4
-      - uses: DeterminateSystems/nix-installer-action@main
-      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - uses: DeterminateSystems/nix-installer-action@ef8a148080ab6020fd15196c2084a2eea5ff2d25  # v22
+      - uses: DeterminateSystems/magic-nix-cache-action@565684385bcd71bad329742eefe8d12f2e765b39  # v13
       - name: Check flake
         if: runner.os == 'Linux'
         run: nix flake check --print-build-logs