diff --git a/.github/dependabot.yml b/.github/dependabot.yml
deleted file mode 100644
index 5c4156c6..00000000
--- a/.github/dependabot.yml
+++ /dev/null
@@ -1,14 +0,0 @@
-version: 2
-updates:
-- package-ecosystem: github-actions
-  directory: "/"
-  schedule:
-    interval: daily
-    timezone: Etc/UTC
-  open-pull-requests-limit: 10
-  reviewers:
-  - str4d
-  assignees:
-  - str4d
-  labels:
-  - "A-CI"
diff --git a/.github/workflows/bench.yml b/.github/workflows/bench.yml
index 060fc87d..1ab40b1b 100644
--- a/.github/workflows/bench.yml
+++ b/.github/workflows/bench.yml
@@ -16,8 +16,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.51.0
-          override: true
+          override: false
       - name: Run benchmark
         run: cargo bench -- --output-format bencher | tee output.txt
       - name: Store benchmark result
diff --git a/.github/workflows/book.yml b/.github/workflows/book.yml
deleted file mode 100644
index e55fb978..00000000
--- a/.github/workflows/book.yml
+++ /dev/null
@@ -1,50 +0,0 @@
-name: halo2 book
-
-on:
-  push:
-    branches:
-      - main
-
-jobs:
-  deploy:
-    runs-on: ubuntu-18.04
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          # Pinned until https://github.com/rust-lang/rust/issues/93476 is fixed.
-          toolchain: nightly-2022-01-18
-          override: true
-
-      - name: Setup mdBook
-        uses: peaceiris/actions-mdbook@v1
-        with:
-          mdbook-version: 'latest'
-
-      - name: Install mdbook-katex
-        uses: actions-rs/cargo@v1
-        with:
-          command: install
-          args: mdbook-katex
-
-      - name: Build halo2 book
-        run: mdbook build book/
-
-      - name: Build latest rustdocs
-        uses: actions-rs/cargo@v1
-        with:
-          command: doc
-          args: --no-deps --workspace --all-features
-        env:
-          RUSTDOCFLAGS: -Z unstable-options --enable-index-page --cfg docsrs --html-in-header ${{ github.workspace }}/katex-header.html
-
-      - name: Move latest rustdocs into book
-        run: |
-          mkdir -p ./book/book/rustdoc
-          mv ./target/doc ./book/book/rustdoc/latest
-
-      - name: Deploy to GitHub Pages
-        uses: peaceiris/actions-gh-pages@v3
-        with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          publish_dir: ./book/book
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8220a062..b1702c60 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,8 +16,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.51.0
-          override: true
+          override: false
       - name: Run tests
         uses: actions-rs/cargo@v1
         with:
@@ -37,8 +36,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.51.0
-          override: true
+          override: false
       - name: Add target
         run: rustup target add ${{ matrix.target }}
       - name: cargo build
@@ -55,8 +53,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.51.0
-          override: true
+          override: false
       # Build benchmarks to prevent bitrot
       - name: Build benchmarks
         uses: actions-rs/cargo@v1
@@ -64,26 +61,6 @@ jobs:
           command: build
           args: --benches --examples --all-features
 
-  book:
-    name: Book tests
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: 1.51.0
-          override: true
-      - name: cargo build
-        uses: actions-rs/cargo@v1
-        with:
-          command: build
-      - name: Setup mdBook
-        uses: peaceiris/actions-mdbook@v1
-        with:
-          mdbook-version: '0.4.5'
-      - name: Test halo2 book
-        run: mdbook test -L target/debug/deps book/
-
   codecov:
     name: Code coverage
     runs-on: ubuntu-latest
@@ -93,8 +70,7 @@ jobs:
       # Use stable for this to ensure that cargo-tarpaulin can be built.
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
-          override: true
+          override: false
       - name: Install cargo-tarpaulin
         uses: actions-rs/cargo@v1
         with:
@@ -118,8 +94,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.51.0
-          override: true
+          override: false
       - name: cargo fetch
         uses: actions-rs/cargo@v1
         with:
@@ -141,8 +116,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.51.0
-          override: true
+          override: false
       - run: rustup component add rustfmt
       - uses: actions-rs/cargo@v1
         with:
diff --git a/.github/workflows/lints-beta.yml b/.github/workflows/lints-beta.yml
deleted file mode 100644
index ed11b50a..00000000
--- a/.github/workflows/lints-beta.yml
+++ /dev/null
@@ -1,27 +0,0 @@
-name: Beta lints
-
-# These lints are only informative, so we only run them directly on branches
-# and not trial-merges of PRs, to reduce noise.
-on: push
-
-jobs:
-  clippy-beta:
-    name: Clippy (beta)
-    timeout-minutes: 30
-    runs-on: ubuntu-latest
-    continue-on-error: true
-
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: beta
-          components: clippy
-          override: true
-      - name: Run Clippy (beta)
-        uses: actions-rs/clippy-check@v1
-        continue-on-error: true
-        with:
-          name: Clippy (beta)
-          token: ${{ secrets.GITHUB_TOKEN }}
-          args: --all-features --all-targets -- -W clippy::all
diff --git a/.github/workflows/lints-stable.yml b/.github/workflows/lints-stable.yml
index e76d7f25..ffeb7937 100644
--- a/.github/workflows/lints-stable.yml
+++ b/.github/workflows/lints-stable.yml
@@ -13,9 +13,8 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.51.0
           components: clippy
-          override: true
+          override: false
       - name: Run clippy
         uses: actions-rs/clippy-check@v1
         with: