diff --git a/.cargo/config b/.cargo/config
index ba32123..a52fad7 100644
--- a/.cargo/config
+++ b/.cargo/config
@@ -1,3 +1,6 @@
+[env]
+RUST_TEST_THREADS = "1"
+
 [target.x86_64-pc-windows-msvc]
 rustflags = ["-Ctarget-feature=+crt-static"]
 
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 8381472..69e9199 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1,8 +1,8 @@
 ## Development
-Rust 1.38.0 or newer is recommended.
+Use the latest version of Rust.
 
-* Run tests (avoid concurrency since the integration tests make real services):
-  * `cargo test -- --test-threads 1`
+* Run tests:
+  * `cargo test`
 * Activate pre-commit hooks (requires Python) to handle formatting/linting:
   ```
   pip install --user pre-commit