diff --git a/.github/actions/install-rust/action.yml b/.github/actions/install-rust/action.yml
index 5aa8505..0d11907 100644
--- a/.github/actions/install-rust/action.yml
+++ b/.github/actions/install-rust/action.yml
@@ -10,16 +10,16 @@ inputs:
 runs:
   using: composite
   steps:
-    - name: Install Rust
+    - name: Select Rust
       shell: bash
       id: select
       run: |
-        # Determine MSRV as N in `1.N.0` by looking at the `rust-version`
-        # located in the root `Cargo.toml`.
-        msrv=$(grep 'rust-version.*1' Cargo.toml | sed 's/.*\.\([0-9]*\)\..*/\1/')
+        # Determine MSRV by looking at the `rust-version` located in the root
+        # `Cargo.toml`.
+        msrv=$(grep 'rust-version.*1' Cargo.toml | sed 's/rust-version *\= *"\([^"]*\)"/\1/')
 
         if [ "${{ inputs.toolchain }}" = "msrv" ]; then
-          echo "version=1.$msrv.0" >> "$GITHUB_OUTPUT"
+          echo "version=$msrv" >> "$GITHUB_OUTPUT"
         else
           echo "version=${{ inputs.toolchain }}" >> "$GITHUB_OUTPUT"
         fi
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 726a7cf..026420a 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -17,15 +17,17 @@ permissions:
 jobs:
   build_and_test:
     name: Build and test
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     strategy:
       matrix:
-        os: [ubuntu-latest, windows-latest, macOS-latest]
+        rust: [msrv, stable, nightly]
 
     steps:
     - uses: actions/checkout@master
 
     - uses: ./.github/actions/install-rust
+      with:
+        toolchain: ${{ matrix.rust }}
 
     - name: Install wasmtime
       uses: bytecodealliance/actions/wasmtime/setup@v1
diff --git a/Cargo.toml b/Cargo.toml
index 6129835..4fbb58b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -59,8 +59,7 @@ license = "Apache-2.0 WITH LLVM-exception"
 repository = "https://github.com/bytecodealliance/wstd"
 keywords = ["WebAssembly", "async", "stdlib", "Components"]
 categories = ["wasm", "asynchronous"]
-# Rust-version policy: stable N-2, same as wasmtime.
-rust-version = "1.89"
+rust-version = "1.88"
 authors = [
     "Yoshua Wuyts <rust@yosh.is>",
     "Pat Hickey <pat@moreproductive.org>",
diff --git a/test-programs/Cargo.toml b/test-programs/Cargo.toml
index ba431b4..f280352 100644
--- a/test-programs/Cargo.toml
+++ b/test-programs/Cargo.toml
@@ -16,6 +16,9 @@ ureq.workspace = true
 cargo_metadata.workspace = true
 heck.workspace = true
 
+[dependencies]
+fs2 = "0.4"
+
 [features]
 default = []
 no-aws = []
diff --git a/test-programs/src/lib.rs b/test-programs/src/lib.rs
index 0d4a83f..a62d166 100644
--- a/test-programs/src/lib.rs
+++ b/test-programs/src/lib.rs
@@ -6,6 +6,9 @@ use std::process::{Child, Command};
 use std::thread::sleep;
 use std::time::Duration;
 
+// Required until msrv over 1.89, at which point locking is available in std
+use fs2::FileExt;
+
 const DEFAULT_SERVER_PORT: u16 = 8081;
 
 /// Manages exclusive access to port 8081, and kills the process when dropped
@@ -31,7 +34,8 @@ impl WasmtimeServe {
         let mut lockfile = std::env::temp_dir();
         lockfile.push(format!("TEST_PROGRAMS_WASMTIME_SERVE_{port}.lock"));
         let lockfile = File::create(&lockfile)?;
-        lockfile.lock()?;
+        // Once msrv reaches 1.89, replace with std's `.lock()` method
+        lockfile.lock_exclusive()?;
 
         // Run wasmtime serve.
         // Enable -Scli because we currently don't have a way to build with the