diff --git a/artiq/firmware/Cargo.lock b/artiq/firmware/Cargo.lock
index 2ff4e8b6b..d4c926fef 100644
--- a/artiq/firmware/Cargo.lock
+++ b/artiq/firmware/Cargo.lock
@@ -157,7 +157,7 @@ dependencies = [
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "logger_artiq 0.0.0",
  "proto 0.0.0",
- "smoltcp 0.4.0 (git+https://github.com/m-labs/smoltcp?rev=bf4ddef)",
+ "smoltcp 0.4.0 (git+https://github.com/m-labs/smoltcp?rev=6f5ae33)",
  "std_artiq 0.0.0",
 ]
 
@@ -183,7 +183,7 @@ dependencies = [
 [[package]]
 name = "smoltcp"
 version = "0.4.0"
-source = "git+https://github.com/m-labs/smoltcp?rev=bf4ddef#bf4ddef87dae0e671dc8041b7fffd03376518e1e"
+source = "git+https://github.com/m-labs/smoltcp?rev=6f5ae33#6f5ae33501827d57926469c6f1a860205a24f7ae"
 dependencies = [
  "byteorder 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -221,7 +221,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum log_buffer 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ec57723b84bbe7bdf76aa93169c9b59e67473317c6de3a83cb2a0f8ccb2aa493"
 "checksum managed 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b5d48e8c30a4363e2981fe4db20527f6ab0f32a243bbc75379dea5a64f60dae4"
 "checksum rustc-cfg 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "56a596b5718bf5e059d59a30af12f7f462a152de147aa462b70892849ee18704"
-"checksum smoltcp 0.4.0 (git+https://github.com/m-labs/smoltcp?rev=bf4ddef)" = "<none>"
+"checksum smoltcp 0.4.0 (git+https://github.com/m-labs/smoltcp?rev=6f5ae33)" = "<none>"
 "checksum walkdir 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "dd7c16466ecc507c7cb5988db03e6eab4aaeab89a5c37a29251fcfd3ac9b7afe"
 "checksum winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)" = "167dc9d6949a9b857f3451275e911c3f44255842c1f7a76f33c55103a909087a"
 "checksum winapi-build 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "2d315eee3b34aca4797b2da6b13ed88266e6d612562a0c46390af8299fc699bc"
diff --git a/artiq/firmware/runtime/Cargo.toml b/artiq/firmware/runtime/Cargo.toml
index 8b654b373..5013d9878 100644
--- a/artiq/firmware/runtime/Cargo.toml
+++ b/artiq/firmware/runtime/Cargo.toml
@@ -37,6 +37,6 @@ features = ["alloc"]
 
 [dependencies.smoltcp]
 git = "https://github.com/m-labs/smoltcp"
-rev = "bf4ddef"
+rev = "6f5ae33"
 default-features = false
 features = ["alloc", "log"]
diff --git a/artiq/firmware/runtime/sched.rs b/artiq/firmware/runtime/sched.rs
index 11d5da676..b69f87da4 100644
--- a/artiq/firmware/runtime/sched.rs
+++ b/artiq/firmware/runtime/sched.rs
@@ -470,6 +470,22 @@ impl<'a> TcpStream<'a> {
         self.as_lower().remote_endpoint()
     }
 
+    pub fn timeout(&self) -> Option<u64> {
+        self.as_lower().timeout()
+    }
+
+    pub fn set_timeout(&self, value: Option<u64>) {
+        self.as_lower().set_timeout(value)
+    }
+
+    pub fn keep_alive(&self) -> Option<u64> {
+        self.as_lower().keep_alive()
+    }
+
+    pub fn set_keep_alive(&self, value: Option<u64>) {
+        self.as_lower().set_keep_alive(value)
+    }
+
     pub fn close(&self) -> Result<()> {
         self.as_lower().close();
         until!(self, TcpSocketLower, |s| !s.is_open())?;
diff --git a/artiq/firmware/runtime/session.rs b/artiq/firmware/runtime/session.rs
index 9feb59d0b..fa698b198 100644
--- a/artiq/firmware/runtime/session.rs
+++ b/artiq/firmware/runtime/session.rs
@@ -634,6 +634,9 @@ pub fn thread(io: Io) {
     loop {
         if listener.can_accept() {
             let mut stream = listener.accept().expect("session: cannot accept");
+            stream.set_timeout(Some(1000));
+            stream.set_keep_alive(Some(500));
+
             match check_magic(&mut stream) {
                 Ok(()) => (),
                 Err(_) => {