diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 415e59ed57..91bdd675c2 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -30,14 +30,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v1
+        uses: actions/checkout@v4
 
       - name: Install Rust
-        uses: actions-rs/toolchain@v1
+        uses: dtolnay/rust-toolchain@stable
         with:
-          profile: minimal
-          toolchain: stable
-          override: true
           components: rustfmt
 
       - name: cargo fmt --check
@@ -75,27 +72,21 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v1
+        uses: actions/checkout@v4
 
       - name: Install Rust (${{ matrix.rust }})
-        uses: actions-rs/toolchain@v1
+        uses: dtolnay/rust-toolchain@stable
         with:
-          profile: minimal
           toolchain: ${{ matrix.rust }}
-          override: true
+
+      - uses: Swatinem/rust-cache@v2
 
       - name: Test
-        uses: actions-rs/cargo@v1
-        with:
-          command: test
-          args: ${{ matrix.features }}
+        run: cargo test ${{ matrix.features }}
 
       - name: Test all benches
         if: matrix.benches
-        uses: actions-rs/cargo@v1
-        with:
-          command: test
-          args: --benches ${{ matrix.features }}
+        run: cargo test --benches ${{ matrix.features }}
 
   msrv:
     name: Check MSRV (${{ matrix.rust }})
@@ -112,20 +103,17 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v1
+        uses: actions/checkout@v4
 
       - name: Install Rust (${{ matrix.rust }})
-        uses: actions-rs/toolchain@v1
+        uses: dtolnay/rust-toolchain@stable
         with:
-          profile: minimal
           toolchain: ${{ matrix.rust }}
-          override: true
+
+      - uses: Swatinem/rust-cache@v2
 
       - name: Check
-        uses: actions-rs/cargo@v1
-        with:
-          command: check
-          args: --features full
+        run: cargo check --features full
 
   miri:
     name: Test with Miri
@@ -134,15 +122,12 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v1
+        uses: actions/checkout@v4
 
       - name: Install Rust
-        uses: actions-rs/toolchain@v1
+        uses: dtolnay/rust-toolchain@nightly
         with:
-          profile: minimal
-          toolchain: nightly
           components: miri
-          override: true
 
       - name: Test
         # Can't enable tcp feature since Miri does not support the tokio runtime
@@ -154,20 +139,18 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v1
+        uses: actions/checkout@v4
 
       - name: Install Rust
-        uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: nightly
-          override: true
+        uses: dtolnay/rust-toolchain@stable
 
       - name: Install cargo-hack
-        run: cargo install cargo-hack
+        uses: taiki-e/install-action@cargo-hack
+
+      - uses: Swatinem/rust-cache@v2
 
       - name: check --feature-powerset
-        run: cargo hack check --feature-powerset --depth 2 --skip ffi -Z avoid-dev-deps
+        run: cargo hack --no-dev-deps check --feature-powerset --depth 2 --skip ffi
 
   deprecated:
     name: Check deprecated on ${{ matrix.rust }}
@@ -182,20 +165,17 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v1
+        uses: actions/checkout@v4
 
       - name: Install Rust (${{ matrix.rust }})
-        uses: actions-rs/toolchain@v1
+        uses: dtolnay/rust-toolchain@stable
         with:
-          profile: minimal
           toolchain: ${{ matrix.rust }}
-          override: true
+
+      - uses: Swatinem/rust-cache@v2
 
       - name: Check
-        uses: actions-rs/cargo@v1
-        with:
-          command: check
-          args: --features full,backports,deprecated
+        run: cargo check --features full,backports,deprecated
 
   ffi:
     name: Test C API (FFI)
@@ -203,69 +183,57 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v1
+        uses: actions/checkout@v4
 
       - name: Install Rust
-        uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: nightly
-          override: true
+        uses: dtolnay/rust-toolchain@stable
 
       - name: Install cbindgen
-        uses: actions-rs/cargo@v1
+        uses: taiki-e/cache-cargo-install-action@v1
         with:
-          command: install
-          args: cbindgen
+          tool: cbindgen
+
+      - uses: Swatinem/rust-cache@v2
 
       - name: Build FFI
-        uses: actions-rs/cargo@v1
+        run: cargo rustc --features client,http1,http2,ffi --crate-type cdylib
         env:
           RUSTFLAGS: --cfg hyper_unstable_ffi
-        with:
-          command: rustc
-          args: --features client,http1,http2,ffi -Z unstable-options --crate-type cdylib
 
       - name: Make Examples
         run: cd capi/examples && make client
 
       - name: Run FFI unit tests
-        uses: actions-rs/cargo@v1
+        run: cargo test --features full,ffi --lib
         env:
           RUSTFLAGS: --cfg hyper_unstable_ffi
-        with:
-          command: test
-          args: --features full,ffi --lib
 
   ffi-header:
     name: Verify hyper.h is up to date
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v1
+        uses: actions/checkout@v4
 
       - name: Install Rust
-        uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: nightly
-          default: true
-          override: true
-          components: cargo
+        uses: dtolnay/rust-toolchain@stable
 
       - name: Install cbindgen
-        uses: actions-rs/cargo@v1
+        uses: taiki-e/cache-cargo-install-action@v1
+        with:
+          tool: cbindgen
+
+      - name: Install cargo-expand
+        uses: taiki-e/cache-cargo-install-action@v1
         with:
-          command: install
-          args: cbindgen
+          tool: cargo-expand
+
+      - uses: Swatinem/rust-cache@v2
 
       - name: Build FFI
-        uses: actions-rs/cargo@v1
+        run: cargo build --features client,http1,http2,ffi
         env:
           RUSTFLAGS: --cfg hyper_unstable_ffi
-        with:
-          command: build
-          args: --features client,http1,http2,ffi
 
       - name: Ensure that hyper.h is up to date
         run: ./capi/gen_header.sh --verify
@@ -276,17 +244,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v1
+        uses: actions/checkout@v4
 
       - name: Install Rust
-        uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: nightly
-          override: true
+        uses: dtolnay/rust-toolchain@nightly
 
       - name: cargo doc
-        uses: actions-rs/cargo@v1
-        with:
-          command: rustdoc
-          args: --features full,ffi -- --cfg docsrs --cfg hyper_unstable_ffi -D broken-intra-doc-links
+        run: cargo rustdoc --features full,ffi -- --cfg docsrs --cfg hyper_unstable_ffi -D broken-intra-doc-links
diff --git a/capi/gen_header.sh b/capi/gen_header.sh
index d0b9c13a32..7a08d3e6ff 100755
--- a/capi/gen_header.sh
+++ b/capi/gen_header.sh
@@ -6,101 +6,44 @@
 set -e
 
 CAPI_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
-
-WORK_DIR=$(mktemp -d)
-
-# check if tmp dir was created
-if [[ ! "$WORK_DIR" || ! -d "$WORK_DIR" ]]; then
-    echo "Could not create temp dir"
-    exit 1
-fi
-
 header_file_backup="$CAPI_DIR/include/hyper.h.backup"
 
 function cleanup {
-    rm -rf "$WORK_DIR"
+    rm -rf "$WORK_DIR" || true
     rm "$header_file_backup" || true
 }
 
 trap cleanup EXIT
 
-mkdir "$WORK_DIR/src"
-
-# Fake a library
-cat > "$WORK_DIR/src/lib.rs" << EOF
-#[path = "$CAPI_DIR/../src/ffi/mod.rs"]
-pub mod ffi;
-EOF
-
-# And its Cargo.toml
-cat > "$WORK_DIR/Cargo.toml" << EOF
-[package]
-name = "hyper"
-version = "0.0.0"
-edition = "2018"
-publish = false
-
-[dependencies]
-# Determined which dependencies we need by running the "cargo rustc" command
-# below and watching the compile error output for references to unknown imports,
-# until we didn't get any errors.
-bytes = "1"
-futures-channel = "0.3"
-futures-util = { version = "0.3", default-features = false, features = ["alloc"] }
-libc = { version = "0.2", optional = true }
-http = "0.2"
-http-body = "0.4"
-tokio = { version = "1", features = ["rt"] }
-
-[features]
-default = [
-    "client",
-    "ffi",
-    "http1",
-]
+WORK_DIR=$(mktemp -d)
 
-http1 = []
-client = []
-ffi = ["libc", "tokio/rt"]
-EOF
+# check if tmp dir was created
+if [[ ! "$WORK_DIR" || ! -d "$WORK_DIR" ]]; then
+    echo "Could not create temp dir"
+    exit 1
+fi
 
 cp "$CAPI_DIR/include/hyper.h" "$header_file_backup"
 
-#cargo metadata --no-default-features --features ffi --format-version 1 > "$WORK_DIR/metadata.json"
-
-cd "${WORK_DIR}" || exit 2
-
 # Expand just the ffi module
-if ! output=$(RUSTFLAGS='--cfg hyper_unstable_ffi' cargo rustc -- -Z unpretty=expanded 2>&1 > expanded.rs); then
-    # As of April 2021 the script above prints a lot of warnings/errors, and
-    # exits with a nonzero return code, but hyper.h still gets generated.
-    #
-    # However, on Github Actions, this will result in automatic "annotations"
-    # being added to files not related to a PR, so if this is `--verify` mode,
-    # then don't show it.
-    #
-    # But yes show it when using it locally.
-    if [[ "--verify" != "$1" ]]; then
-        echo "$output"
-    fi
+if ! RUSTFLAGS='--cfg hyper_unstable_ffi' cargo expand --features client,http1,http2,ffi ::ffi 2> $WORK_DIR/expand_stderr.err > $WORK_DIR/expanded.rs; then
+    cat $WORK_DIR/expand_stderr.err
 fi
 
-# Replace the previous copy with the single expanded file
-rm -rf ./src
-mkdir src
-mv expanded.rs src/lib.rs
-
-
 # Bindgen!
 if ! cbindgen \
     --config "$CAPI_DIR/cbindgen.toml" \
     --lockfile "$CAPI_DIR/../Cargo.lock" \
     --output "$CAPI_DIR/include/hyper.h" \
-    "${@}"; then
+    "${@}"\
+    $WORK_DIR/expanded.rs 2> $WORK_DIR/cbindgen_stderr.err; then
     bindgen_exit_code=$?
     if [[ "--verify" == "$1" ]]; then
-        echo "diff generated (<) vs backup (>)"
-        diff "$CAPI_DIR/include/hyper.h" "$header_file_backup"
+        echo "Changes from previous header (old < > new)"
+        diff -u "$header_file_backup" "$CAPI_DIR/include/hyper.h"
+    else
+        echo "cbindgen failed:"
+        cat $WORK_DIR/cbindgen_stderr.err
     fi
     exit $bindgen_exit_code
 fi