diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 457f307..4254c4d 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -13,19 +13,21 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Build
       run: cargo build --verbose
     - name: Run tests
       run: cargo test --verbose
-    - name: Run tests for serde feature
+    - name: Run tests on no_std
+      run: cargo test --no-default-features --verbose
+    - name: Run tests for serde
       run: cargo test --features serde --verbose
       
   miri:
     name: "Miri"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Install Miri
         run: |
           rustup toolchain install nightly --component miri
@@ -33,57 +35,53 @@ jobs:
           cargo miri setup
       - name: Test with Miri
         run: MIRIFLAGS=-Zmiri-strict-provenance cargo miri test
-      - name: Run tests for serde feature
-        run: MIRIFLAGS=-Zmiri-strict-provenance cargo miri test --features serde
   
   fmt:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: stable
-          profile: minimal
           components: rustfmt
-          override: true
-      - uses: actions-rs/cargo@v1
+      - run: cargo fmt --all -- --check
+
+  msrv:
+    name: Rust ${{matrix.rust}}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        rust: [1.63.0, 1.64.0]
+    timeout-minutes: 45
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@master
         with:
-          command: fmt
-          args: --all -- --check
-          
-          
+          toolchain: ${{matrix.rust}}
+      - run: cargo build
+      - run: cargo test
+      - run: cargo test --no-default-features
+      - run: cargo test --features serde
+
   clippy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@master
         with:
             toolchain: stable
-            profile: minimal
             components: clippy
-            override: true
-      - uses: actions-rs/clippy-check@v1
-        env:
-          PWD: ${{ env.GITHUB_WORKSPACE }}
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}
-          args: --workspace --tests --examples
-          
-          
+      - run: cargo clippy --workspace --tests --examples
+
   docs:
     runs-on: ubuntu-latest
     env:
       RUSTDOCFLAGS: -Dwarnings
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: stable
-          profile: minimal
-          components: rust-docs
-          override: true
-      - uses: swatinem/rust-cache@v1
-      - uses: actions-rs/cargo@v1
-        with:
-          command: doc
-          args: --workspace --no-deps
+      - uses: swatinem/rust-cache@v2
+      - run: cargo doc --workspace --no-deps
diff --git a/Cargo.toml b/Cargo.toml
index 9c343c9..b7bdd17 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,7 +9,8 @@ homepage = "https://github.com/contain-rs/bit-set"
 documentation = "https://docs.rs/bit-set/"
 keywords = ["data-structures", "bitset"]
 readme = "README.md"
-edition = "2015"
+edition = "2021"
+rust-version = "1.63"
 
 [dependencies]
 serde = { version = "1.0", features = ["derive"], optional = true }
diff --git a/README.md b/README.md
index 28a9adb..3fa4e26 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@
 [![crates.io][crates.io shield]][crates.io link]
 [![Documentation][docs.rs badge]][docs.rs link]
 ![Rust CI][github ci badge]
-[![rustc 1.0+]][Rust 1.0]
+![rustc 1.63+]
 <br />
 <br />
 [![Dependency Status][deps.rs status]][deps.rs link]
@@ -21,9 +21,8 @@
 [crates.io link]: https://crates.io/crates/bit-set
 [docs.rs badge]: https://docs.rs/bit-set/badge.svg?version=0.8.0
 [docs.rs link]: https://docs.rs/bit-set/0.8.0/bit_set/
-[github ci badge]: https://github.com/contain-rs/linked-hash-map/workflows/Rust/badge.svg?branch=master
-[rustc 1.0+]: https://img.shields.io/badge/rustc-1.0%2B-blue.svg
-[Rust 1.0]: https://blog.rust-lang.org/2015/05/15/Rust-1.0.html
+[github ci badge]: https://github.com/contain-rs/bit-set/workflows/Rust/badge.svg?branch=master
+[rustc 1.63+]: https://img.shields.io/badge/rustc-1.63%2B-blue.svg
 [deps.rs status]: https://deps.rs/crate/bit-set/0.8.0/status.svg
 [deps.rs link]: https://deps.rs/crate/bit-set/0.8.0
 [shields.io download count]: https://img.shields.io/crates/d/bit-set.svg
diff --git a/src/lib.rs b/src/lib.rs
index 30bf8ce..6d4a643 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -51,11 +51,6 @@
 #![doc(html_root_url = "https://docs.rs/bit-set/0.8.0")]
 #![no_std]
 
-extern crate bit_vec;
-
-#[cfg(feature = "serde")]
-extern crate serde;
-
 #[cfg(any(test, feature = "std"))]
 extern crate std;