diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a18e6b5..1b5b798 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,10 +21,10 @@ jobs:
           # We need to fetch the entire history so clippy can run the
           # e2e-example/client build script.
           fetch-depth: 0
-      - uses: dtolnay/rust-toolchain@stable
+      - uses: dtolnay/rust-toolchain@686976e191b89faba57d3206551f0f330d8cb249 # stable
         with:
           components: rustfmt, clippy
-      - uses: taiki-e/install-action@just
+      - uses: taiki-e/install-action@0c0305935e3ef3b9e6205d176ec55ee4fce34cca # just
       - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
         with:
           key: partition-${{ matrix.partition }}
@@ -54,14 +54,14 @@ jobs:
           # We need to fetch the entire history so the tests can run merge-base
           # operations.
           fetch-depth: 0
-      - uses: dtolnay/rust-toolchain@master
+      - uses: dtolnay/rust-toolchain@e2a55d2ffb04f378e9626c28d38b36d230d1e12f # master
         with:
           toolchain: ${{ matrix.rust-version }}
       - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
         with:
           key: partition-${{ matrix.partition }}
-      - uses: taiki-e/install-action@nextest
-      - uses: taiki-e/install-action@v2
+      - uses: taiki-e/install-action@2eb6de229bc778f7df20e106e4b34e9a364c73e6 # nextest
+      - uses: taiki-e/install-action@1168f6810a3cb30a3514bf5756a3b7f0422c6df8 # v2
         with:
           tool: jj-cli
       - name: Build
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index ca4d1a0..a1e5213 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -21,7 +21,7 @@ jobs:
       - uses: rust-lang/crates-io-auth-action@v1
         id: auth
       - name: Install Rust
-        uses: dtolnay/rust-toolchain@stable
+        uses: dtolnay/rust-toolchain@686976e191b89faba57d3206551f0f330d8cb249 # stable
       - name: Install cargo release
         uses: taiki-e/install-action@83ac0ad63c0167e6f06796fab0fce28db1bf3db0 # v2
         with: