diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 892af1e..919c97b 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -1,41 +1,57 @@
 name: CI
 on: [push, pull_request]
 
+env:
+  CARGO_REGISTRIES_CRATES_IO_PROTOCOL: sparse
+
 jobs:
   test:
     name: Test
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        rust: ["1.63", stable, beta, nightly]
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        rust: [stable, beta, nightly]
+        os: [ubuntu-latest, macos-14, windows-latest]
     steps:
     - uses: actions/checkout@master
     - name: Install Rust (rustup)
-      run: rustup update ${{ matrix.rust }} --no-self-update && rustup default ${{ matrix.rust }}
+      run: |
+        rustup toolchain install ${{ matrix.rust }} --no-self-update --profile minimal
+        rustup default ${{ matrix.rust }}
       shell: bash
 
-    - run: cargo test
+    - uses: Swatinem/rust-cache@v2
+
+    - run: cargo test --locked
+
+    - name: Cache make compiled
+      if: ${{ !startsWith(matrix.os, 'windows') }}
+      id: cache-make
+      uses: actions/cache@v4
+      with:
+        path: /usr/local/bin/make
+        key: ${{ runner.os }}-make-4.4.1
 
     # Compile it from source (temporarily)
     - name: Make GNU Make from source
-      if: ${{ !startsWith(matrix.os, 'windows') }}
+      if: ${{ !startsWith(matrix.os, 'windows') && steps.cache-make.outputs.cache-hit != 'true' }}
       env:
         VERSION: "4.4.1"
       shell: bash
       run: |
-        wget -q "https://ftp.gnu.org/gnu/make/make-${VERSION}.tar.gz"
-        tar zxf "make-${VERSION}.tar.gz"
+        curl "https://ftp.gnu.org/gnu/make/make-${VERSION}.tar.gz" | tar xz
         pushd "make-${VERSION}"
         ./configure
-        make
+        make -j 4
         popd
-        cp -rp "make-${VERSION}/make" .
+        cp -p "make-${VERSION}/make" /usr/local/bin
+
     - name: Test against GNU Make from source
       if: ${{ !startsWith(matrix.os, 'windows') }}
       shell: bash
-      run:
-        MAKE="${PWD}/make" cargo test
+      run: cargo test --locked
+      env:
+        MAKE: /usr/local/bin/make
 
   rustfmt:
     name: Rustfmt
@@ -63,3 +79,19 @@ jobs:
           git -c user.name='ci' -c user.email='ci' commit -m init
           git push -f -q https://git:${{ secrets.github_token }}@github.com/${{ github.repository }} HEAD:gh-pages
         if: github.event_name == 'push' && github.event.ref == 'refs/heads/master'
+
+  msrv:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-14, windows-latest]
+    steps:
+    - uses: actions/checkout@master
+    - name: Install Rust (rustup)
+      run: rustup toolchain install nightly --no-self-update --profile minimal
+      shell: bash
+
+    - uses: taiki-e/install-action@cargo-hack
+    - uses: Swatinem/rust-cache@v2
+
+    - run: cargo hack check --lib --rust-version --ignore-private --locked
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..7531774
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,142 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "bitflags"
+version = "2.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4682ae6287fcf752ecaabbfcc7b6f9b72aa33933dc23a554d853aea8eea8635"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "errno"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a258e46cdc063eb8519c00b9fc845fc47bcfca4130e2f08e88665ceda8474245"
+dependencies = [
+ "libc",
+ "windows-sys",
+]
+
+[[package]]
+name = "fastrand"
+version = "2.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "25cbce373ec4653f1a01a31e8a5e5ec0c622dc27ff9c4e6606eefef5cbbed4a5"
+
+[[package]]
+name = "jobserver"
+version = "0.1.28"
+dependencies = [
+ "libc",
+ "tempfile",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.152"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13e3bf6590cbc649f4d1a3eefc9d5d6eb746f5200ffb04e5e142700b8faa56e7"
+
+[[package]]
+name = "linux-raw-sys"
+version = "0.4.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4cd1a83af159aa67994778be9070f0ae1bd732942279cabb14f86f986a21456"
+
+[[package]]
+name = "rustix"
+version = "0.38.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6ea3e1a662af26cd7a3ba09c0297a31af215563ecf42817c98df621387f4e949"
+dependencies = [
+ "bitflags",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys",
+]
+
+[[package]]
+name = "tempfile"
+version = "3.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85b77fafb263dd9d05cbeac119526425676db3784113aa9295c88498cbf8bff1"
+dependencies = [
+ "cfg-if",
+ "fastrand",
+ "rustix",
+ "windows-sys",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
+dependencies = [
+ "windows-targets",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8a18201040b24831fbb9e4eb208f8892e1f50a37feb53cc7ff887feb8f50e7cd"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cb7764e35d4db8a7921e09562a0304bf2f93e0a51bfccee0bd0bb0b666b015ea"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbaa0368d4f1d2aaefc55b6fcfee13f41544ddf36801e793edbbfd7d7df075ef"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a28637cb1fa3560a16915793afb20081aba2c92ee8af57b4d5f28e4b3e7df313"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ffe5e8e31046ce6230cc7215707b816e339ff4d4d67c65dffa206fd0f7aa7b9a"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3d6fa32db2bc4a2f5abeacf2b69f7992cd09dca97498da74a151a3132c26befd"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a657e1e9d3f514745a572a6846d3c7aa7dbe1658c056ed9c3344c4109a6949e"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dff9641d1cd4be8d1a070daf9e3773c5f67e78b4d9d42263020c057706765c04"
diff --git a/Cargo.toml b/Cargo.toml
index 9e94b53..42e72ad 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,14 +13,10 @@ edition = "2021"
 rust-version = "1.63"
 
 [target.'cfg(unix)'.dependencies]
-libc = "0.2.50"
+libc = "0.2.72"
 
 [dev-dependencies]
-futures = "0.1"
-num_cpus = "1.0"
-tempfile = "3"
-tokio-core = "0.1"
-tokio-process = "0.2"
+tempfile = "3.10.1"
 
 [[test]]
 name = "client"
diff --git a/tests/client.rs b/tests/client.rs
index 2516b8c..f10a10c 100644
--- a/tests/client.rs
+++ b/tests/client.rs
@@ -7,11 +7,7 @@ use std::sync::mpsc;
 use std::sync::Arc;
 use std::thread;
 
-use futures::future::{self, Future};
-use futures::stream::{self, Stream};
 use jobserver::Client;
-use tokio_core::reactor::Core;
-use tokio_process::CommandExt;
 
 macro_rules! t {
     ($e:expr) => {
@@ -24,9 +20,9 @@ macro_rules! t {
 
 struct Test {
     name: &'static str,
-    f: &'static dyn Fn(),
+    f: &'static (dyn Fn() + Send + Sync),
     make_args: &'static [&'static str],
-    rule: &'static dyn Fn(&str) -> String,
+    rule: &'static (dyn Fn(&str) -> String + Send + Sync),
 }
 
 const TESTS: &[Test] = &[
@@ -118,9 +114,7 @@ fn main() {
     let me = me.to_str().unwrap();
     let filter = env::args().nth(1);
 
-    let mut core = t!(Core::new());
-
-    let futures = TESTS
+    let join_handles = TESTS
         .iter()
         .filter(|test| match filter {
             Some(ref s) => test.name.contains(s),
@@ -138,33 +132,33 @@ all:
                 (test.rule)(me)
             );
             t!(t!(File::create(td.path().join("Makefile"))).write_all(makefile.as_bytes()));
-            let prog = env::var("MAKE").unwrap_or_else(|_| "make".to_string());
-            let mut cmd = Command::new(prog);
-            cmd.args(test.make_args);
-            cmd.current_dir(td.path());
-            future::lazy(move || {
-                cmd.output_async().map(move |e| {
-                    drop(td);
-                    (test, e)
-                })
+            thread::spawn(move || {
+                let prog = env::var("MAKE").unwrap_or_else(|_| "make".to_string());
+                let mut cmd = Command::new(prog);
+                cmd.args(test.make_args);
+                cmd.current_dir(td.path());
+
+                (test, cmd.output().unwrap())
             })
         })
         .collect::<Vec<_>>();
 
-    println!("\nrunning {} tests\n", futures.len());
+    println!("\nrunning {} tests\n", join_handles.len());
 
-    let stream = stream::iter(futures.into_iter().map(Ok)).buffer_unordered(num_cpus::get());
+    let failures = join_handles
+        .into_iter()
+        .filter_map(|join_handle| {
+            let (test, output) = join_handle.join().unwrap();
 
-    let mut failures = Vec::new();
-    t!(core.run(stream.for_each(|(test, output)| {
-        if output.status.success() {
-            println!("test {} ... ok", test.name);
-        } else {
-            println!("test {} ... FAIL", test.name);
-            failures.push((test, output));
-        }
-        Ok(())
-    })));
+            if output.status.success() {
+                println!("test {} ... ok", test.name);
+                None
+            } else {
+                println!("test {} ... FAIL", test.name);
+                Some((test, output))
+            }
+        })
+        .collect::<Vec<_>>();
 
     if failures.is_empty() {
         println!("\ntest result: ok\n");