diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 87d2ef8..e21c17f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -17,14 +17,14 @@ jobs:
       RUSTFLAGS: -D warnings
     steps:
       - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5.0.1
-      - uses: dtolnay/rust-toolchain@stable
+      - uses: dtolnay/rust-toolchain@29eef336d9b2848a0b548edc03f92a220660cdb8 # stable
         with:
           components: rustfmt, clippy
       - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
         with:
           key: partition-${{ matrix.partition }}
       - name: Install just, cargo-hack, and cargo-sync-rdme
-        uses: taiki-e/install-action@v2
+        uses: taiki-e/install-action@3235f8901fd37ffed0052b276cec25a362fb82e9 # v2
         with:
           tool: just,cargo-hack,cargo-sync-rdme
       - name: Lint (clippy)
@@ -35,7 +35,7 @@ jobs:
         run: just rustdoc
       # Pin to a specific nightly for compatibility with cargo-sync-rdme.
       - name: Install nightly toolchain for cargo-sync-rdme
-        uses: dtolnay/rust-toolchain@master
+        uses: dtolnay/rust-toolchain@3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9 # master
         with:
           toolchain: nightly-2026-04-30
       - name: Regenerate readmes
@@ -57,15 +57,15 @@ jobs:
       RUSTFLAGS: -D warnings
     steps:
       - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-      - uses: dtolnay/rust-toolchain@master
+      - uses: dtolnay/rust-toolchain@3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9 # master
         with:
           toolchain: ${{ matrix.rust-version }}
       - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
         with:
           key: partition-${{ matrix.partition }}
-      - uses: taiki-e/install-action@cargo-hack
-      - uses: taiki-e/install-action@just
-      - uses: taiki-e/install-action@nextest
+      - uses: taiki-e/install-action@8253f5d87514ffed213b44025b41ac5a98269c6a # cargo-hack
+      - uses: taiki-e/install-action@31aff3cbbd5cedd6280320e7d7871dd39147ed4c # just
+      - uses: taiki-e/install-action@285e94bf531e72a83c0923d52526fabb44c3b169 # nextest
       - name: Build
         run: just powerset --partition ${{ matrix.partition }}/10 build
       - name: Run tests
@@ -86,11 +86,11 @@ jobs:
       RUSTFLAGS: -D warnings
     steps:
       - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-      - uses: dtolnay/rust-toolchain@master
+      - uses: dtolnay/rust-toolchain@3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9 # master
         with:
           toolchain: ${{ matrix.rust-version }}
       - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
-      - uses: taiki-e/install-action@cross
+      - uses: taiki-e/install-action@c871483f1fb82bb29102989f63fab5e26d1b1305 # cross
       - name: Check
         run: cross check --target thumbv7em-none-eabi --no-default-features -p iddqd
 
@@ -121,15 +121,15 @@ jobs:
       MIRIFLAGS: ${{ matrix.miri-flags }}
     steps:
       - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
-      - uses: dtolnay/rust-toolchain@master
+      - uses: dtolnay/rust-toolchain@3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9 # master
         with:
           toolchain: nightly
           components: miri
       - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
         with:
           key: miri-${{ matrix.aliasing-model }}
-      - uses: taiki-e/install-action@cargo-hack
-      - uses: taiki-e/install-action@nextest
+      - uses: taiki-e/install-action@8253f5d87514ffed213b44025b41ac5a98269c6a # cargo-hack
+      - uses: taiki-e/install-action@285e94bf531e72a83c0923d52526fabb44c3b169 # nextest
       # Run tests for all crates containing unsafe code. Currently, that's just
       # iddqd.
       - name: Run tests
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 95997f8..1af5b43 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@29eef336d9b2848a0b548edc03f92a220660cdb8 # stable
       - name: Install cargo release
         uses: taiki-e/install-action@62da238c048aa0f865cc5a322082957d34e7fc1a # v2
         with: