diff --git a/Cargo.lock b/Cargo.lock
index 1578b01..9c4c3ba 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -719,6 +719,16 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "irtt-integration-tests"
+version = "0.0.0"
+dependencies = [
+ "irtt-client",
+ "irtt-proto",
+ "irtt-server",
+ "tokio",
+]
+
 [[package]]
 name = "irtt-proto"
 version = "0.5.0"
@@ -734,7 +744,6 @@ name = "irtt-server"
 version = "0.5.0"
 dependencies = [
  "getrandom 0.4.3",
- "irtt-client",
  "irtt-proto",
  "nix 0.31.3",
  "socket2",
diff --git a/Cargo.toml b/Cargo.toml
index d2407dc..c2d8201 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -5,6 +5,7 @@ members = [
     "crates/irtt-server",
     "crates/irtt-stats",
     "crates/irtt-cli",
+    "crates/irtt-integration-tests",
 ]
 resolver = "2"
 
diff --git a/crates/irtt-client/src/async_client/in_tree_server_support.rs b/crates/irtt-client/src/async_client/in_tree_server_support.rs
new file mode 100644
index 0000000..0375aa3
--- /dev/null
+++ b/crates/irtt-client/src/async_client/in_tree_server_support.rs
@@ -0,0 +1,82 @@
+//! A real `irtt-server` running in-process, for tests that need to prove
+//! `AsyncClient` and the blocking `Client` are equivalent against a real peer.
+//!
+//! This duplicates `crates/irtt-integration-tests/tests/support/in_tree_server.rs`
+//! rather than depending on it: this module backs private (`super::*`) unit
+//! tests here, while the integration crate covers black-box client/server
+//! behavior, and neither can depend on the other's test-only code.
+
+use std::{
+    net::{IpAddr, Ipv4Addr, SocketAddr},
+    sync::mpsc,
+    thread::{self, JoinHandle},
+    time::Duration,
+};
+
+use irtt_server::{Server, ServerConfig};
+use tokio::sync::oneshot;
+
+const STARTUP_TIMEOUT: Duration = Duration::from_secs(2);
+
+pub struct InTreeServer {
+    pub addr: SocketAddr,
+    shutdown: Option<oneshot::Sender<()>>,
+    done: Option<JoinHandle<Result<(), irtt_server::ServerRuntimeError>>>,
+}
+
+impl InTreeServer {
+    pub fn start(config: ServerConfig) -> Self {
+        let (startup_tx, startup_rx) = mpsc::sync_channel(1);
+        let (shutdown_tx, shutdown_rx) = oneshot::channel();
+        let done = thread::spawn(move || {
+            let runtime = tokio::runtime::Builder::new_current_thread()
+                .enable_all()
+                .build()
+                .expect("failed to build in-tree test server runtime");
+            runtime.block_on(async move {
+                let bind_addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::LOCALHOST), 0);
+                let mut server = Server::bind(bind_addr, config).await?;
+                startup_tx
+                    .send(server.local_addr()?)
+                    .expect("test stopped waiting for in-tree server startup");
+                server
+                    .run(async {
+                        let _ = shutdown_rx.await;
+                    })
+                    .await
+            })
+        });
+
+        let addr = match startup_rx.recv_timeout(STARTUP_TIMEOUT) {
+            Ok(addr) => addr,
+            Err(error) => {
+                let _ = shutdown_tx.send(());
+                let result = done.join().expect("in-tree test server thread panicked");
+                panic!("in-tree test server failed before startup ({error}): {result:?}");
+            }
+        };
+
+        Self {
+            addr,
+            shutdown: Some(shutdown_tx),
+            done: Some(done),
+        }
+    }
+
+    fn stop_inner(&mut self) {
+        if let Some(shutdown) = self.shutdown.take() {
+            let _ = shutdown.send(());
+        }
+        if let Some(done) = self.done.take() {
+            done.join()
+                .expect("in-tree test server thread panicked")
+                .expect("in-tree test server stopped with an error");
+        }
+    }
+}
+
+impl Drop for InTreeServer {
+    fn drop(&mut self) {
+        self.stop_inner();
+    }
+}
diff --git a/crates/irtt-client/src/async_client/tests.rs b/crates/irtt-client/src/async_client/tests.rs
index 9e1278b..eb02a86 100644
--- a/crates/irtt-client/src/async_client/tests.rs
+++ b/crates/irtt-client/src/async_client/tests.rs
@@ -14,7 +14,7 @@ use irtt_proto::{
 };
 use tokio::runtime::{Builder, Runtime};
 
-#[path = "../../tests/support/in_tree_server.rs"]
+#[path = "in_tree_server_support.rs"]
 mod in_tree_server;
 
 use super::*;
diff --git a/crates/irtt-integration-tests/Cargo.toml b/crates/irtt-integration-tests/Cargo.toml
new file mode 100644
index 0000000..198dc7f
--- /dev/null
+++ b/crates/irtt-integration-tests/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "irtt-integration-tests"
+version = "0.0.0"
+edition.workspace = true
+rust-version.workspace = true
+publish = false
+
+[dependencies]
+irtt-client = { workspace = true, features = ["ancillary", "tokio"] }
+irtt-server.workspace = true
+irtt-proto.workspace = true
+tokio = { version = "1.53.1", default-features = false, features = ["rt", "net", "time", "sync", "macros"] }
diff --git a/crates/irtt-server/tests/async_client.rs b/crates/irtt-integration-tests/tests/async_client.rs
similarity index 100%
rename from crates/irtt-server/tests/async_client.rs
rename to crates/irtt-integration-tests/tests/async_client.rs
diff --git a/crates/irtt-client/tests/server_fill.rs b/crates/irtt-integration-tests/tests/fill_negotiation.rs
similarity index 100%
rename from crates/irtt-client/tests/server_fill.rs
rename to crates/irtt-integration-tests/tests/fill_negotiation.rs
diff --git a/crates/irtt-server/tests/server_fill.rs b/crates/irtt-integration-tests/tests/fill_wire_bytes.rs
similarity index 100%
rename from crates/irtt-server/tests/server_fill.rs
rename to crates/irtt-integration-tests/tests/fill_wire_bytes.rs
diff --git a/crates/irtt-client/tests/hmac.rs b/crates/irtt-integration-tests/tests/hmac.rs
similarity index 100%
rename from crates/irtt-client/tests/hmac.rs
rename to crates/irtt-integration-tests/tests/hmac.rs
diff --git a/crates/irtt-client/tests/large_packets.rs b/crates/irtt-integration-tests/tests/large_packets.rs
similarity index 100%
rename from crates/irtt-client/tests/large_packets.rs
rename to crates/irtt-integration-tests/tests/large_packets.rs
diff --git a/crates/irtt-server/tests/negotiation_policy.rs b/crates/irtt-integration-tests/tests/negotiation_policy.rs
similarity index 100%
rename from crates/irtt-server/tests/negotiation_policy.rs
rename to crates/irtt-integration-tests/tests/negotiation_policy.rs
diff --git a/crates/irtt-client/tests/protocol_options.rs b/crates/irtt-integration-tests/tests/protocol_options.rs
similarity index 100%
rename from crates/irtt-client/tests/protocol_options.rs
rename to crates/irtt-integration-tests/tests/protocol_options.rs
diff --git a/crates/irtt-client/tests/protocol_options/backend_smoke.rs b/crates/irtt-integration-tests/tests/protocol_options/backend_smoke.rs
similarity index 100%
rename from crates/irtt-client/tests/protocol_options/backend_smoke.rs
rename to crates/irtt-integration-tests/tests/protocol_options/backend_smoke.rs
diff --git a/crates/irtt-client/tests/support/in_tree_server.rs b/crates/irtt-integration-tests/tests/support/in_tree_server.rs
similarity index 100%
rename from crates/irtt-client/tests/support/in_tree_server.rs
rename to crates/irtt-integration-tests/tests/support/in_tree_server.rs
diff --git a/crates/irtt-client/tests/support/mod.rs b/crates/irtt-integration-tests/tests/support/mod.rs
similarity index 100%
rename from crates/irtt-client/tests/support/mod.rs
rename to crates/irtt-integration-tests/tests/support/mod.rs
diff --git a/crates/irtt-client/tests/support/real_irtt.rs b/crates/irtt-integration-tests/tests/support/real_irtt.rs
similarity index 100%
rename from crates/irtt-client/tests/support/real_irtt.rs
rename to crates/irtt-integration-tests/tests/support/real_irtt.rs
diff --git a/crates/irtt-server/tests/traffic_class.rs b/crates/irtt-integration-tests/tests/traffic_class.rs
similarity index 100%
rename from crates/irtt-server/tests/traffic_class.rs
rename to crates/irtt-integration-tests/tests/traffic_class.rs
diff --git a/crates/irtt-server/tests/wildcard_source.rs b/crates/irtt-integration-tests/tests/wildcard_source.rs
similarity index 100%
rename from crates/irtt-server/tests/wildcard_source.rs
rename to crates/irtt-integration-tests/tests/wildcard_source.rs
diff --git a/crates/irtt-server/Cargo.toml b/crates/irtt-server/Cargo.toml
index 0cb7398..0d1027e 100644
--- a/crates/irtt-server/Cargo.toml
+++ b/crates/irtt-server/Cargo.toml
@@ -23,6 +23,3 @@ tokio = { version = "1.53.1", default-features = false, features = ["rt", "net",
 # source-selection path here; elsewhere a wildcard bind is refused.
 [target.'cfg(any(target_os = "linux", target_os = "macos", target_os = "freebsd"))'.dependencies]
 nix = { version = "0.31.3", default-features = false, features = ["net", "uio"] }
-
-[dev-dependencies]
-irtt-client = { workspace = true, features = ["ancillary", "tokio"] }