diff --git a/Cargo.toml b/Cargo.toml
index 1cfd314..366c3a9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -54,7 +54,7 @@ walkdir = "2.3.3"
 [features]
 default = ["compare", "foreign_document_test"]
 compare = []
-foreign_document_test = ["compare", "dep:tokio", "dep:futures"]
+foreign_document_test = ["compare", "dep:tokio", "dep:futures", "tokio/sync"]
 tracing = ["dep:opentelemetry", "dep:opentelemetry-otlp", "dep:opentelemetry-semantic-conventions", "dep:tokio", "dep:tracing", "dep:tracing-opentelemetry", "dep:tracing-subscriber"]
 
 # Optimized build for any sort of release.
diff --git a/src/bin_foreign_document_test.rs b/src/bin_foreign_document_test.rs
index ae5d276..4bb471a 100644
--- a/src/bin_foreign_document_test.rs
+++ b/src/bin_foreign_document_test.rs
@@ -6,9 +6,9 @@ use std::path::PathBuf;
 
 use futures::future::BoxFuture;
 use futures::future::FutureExt;
-use futures::stream::FuturesUnordered;
 use organic::compare::run_anonymous_compare;
 use organic::compare::run_compare_on_file;
+use tokio::sync::Semaphore;
 
 #[cfg(feature = "tracing")]
 use crate::init_tracing::init_telemetry;
@@ -44,7 +44,6 @@ async fn main_body() -> Result<(), Box<dyn std::error::Error>> {
     let single_file = TestConfig::SingleFile(SingleFile {
         file_path: PathBuf::from("/tmp/test.org"),
     });
-    let mut futs = FuturesUnordered::new();
     // let result = single_file.run_test().await;
     let result = tokio::spawn(single_file.run_test()).await;
     println!("{:?}", result);
@@ -57,6 +56,8 @@ async fn main_body() -> Result<(), Box<dyn std::error::Error>> {
     Ok(())
 }
 
+static TEST_PERMITS: Semaphore = Semaphore::const_new(8);
+
 #[derive(Debug)]
 enum TestConfig {
     TestLayer(TestLayer),
@@ -112,6 +113,7 @@ impl TestConfig {
 
 impl SingleFile {
     async fn run_test(self) -> SingleFileResult {
+        let _permit = TEST_PERMITS.acquire().await.unwrap();
         let result = run_compare_on_file(&self.file_path);
         SingleFileResult {
             file_path: self.file_path,