diff --git a/artiq/firmware/Cargo.lock b/artiq/firmware/Cargo.lock
index 353118496..0fcaac872 100644
--- a/artiq/firmware/Cargo.lock
+++ b/artiq/firmware/Cargo.lock
@@ -165,7 +165,7 @@ dependencies = [
  "log 0.3.8 (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=960b001)",
+ "smoltcp 0.4.0 (git+https://github.com/m-labs/smoltcp?rev=507d2fe)",
  "std_artiq 0.0.0",
 ]
 
@@ -200,7 +200,7 @@ dependencies = [
 [[package]]
 name = "smoltcp"
 version = "0.4.0"
-source = "git+https://github.com/m-labs/smoltcp?rev=960b001#960b0012a09d37dde1d86b28bb5531316f606bfd"
+source = "git+https://github.com/m-labs/smoltcp?rev=507d2fe#507d2fe0ea390ec309d2e900a9d0d4a70a3dfa3c"
 dependencies = [
  "byteorder 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -245,7 +245,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum managed 0.4.0 (git+https://github.com/m-labs/rust-managed.git?rev=629a6786a1cf1692015f464ed16c04eafa5cb8d1)" = "<none>"
 "checksum rustc-cfg 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "56a596b5718bf5e059d59a30af12f7f462a152de147aa462b70892849ee18704"
 "checksum same-file 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "d931a44fdaa43b8637009e7632a02adc4f2b2e0733c08caa4cf00e8da4a117a7"
-"checksum smoltcp 0.4.0 (git+https://github.com/m-labs/smoltcp?rev=960b001)" = "<none>"
+"checksum smoltcp 0.4.0 (git+https://github.com/m-labs/smoltcp?rev=507d2fe)" = "<none>"
 "checksum walkdir 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)" = "bb08f9e670fab86099470b97cd2b252d6527f0b3cc1401acdb595ffc9dd288ff"
 "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 f9db55dee..00f1ca121 100644
--- a/artiq/firmware/runtime/Cargo.toml
+++ b/artiq/firmware/runtime/Cargo.toml
@@ -38,6 +38,6 @@ features = ["alloc"]
 
 [dependencies.smoltcp]
 git = "https://github.com/m-labs/smoltcp"
-rev = "960b001"
+rev = "507d2fe"
 default-features = false
-features = ["alloc", "log", "socket-tcp"]
+features = ["alloc", "log", "proto-ipv4", "socket-tcp"]
diff --git a/artiq/firmware/runtime/lib.rs b/artiq/firmware/runtime/lib.rs
index 997d77a27..f7e68a3fb 100644
--- a/artiq/firmware/runtime/lib.rs
+++ b/artiq/firmware/runtime/lib.rs
@@ -106,7 +106,7 @@ fn startup() {
     //         where U: smoltcp::wire::pretty_print::PrettyPrint {
     //     let seconds = timestamp / 1000;
     //     let micros  = timestamp % 1000 * 1000;
-    //     print!("\x1b[37m[{:6}.{:06}s]\n{}\x1b[0m", seconds, micros, printer)
+    //     print!("\x1b[37m[{:6}.{:06}s]\n{}\x1b[0m\n", seconds, micros, printer)
     // }
 
     let net_device = unsafe { ethmac::EthernetDevice::new() };
@@ -156,11 +156,16 @@ fn startup() {
     loop {
         scheduler.run();
 
-        match interface.poll(&mut *borrow_mut!(scheduler.sockets()),
-                             board::clock::get_ms()) {
-            Ok(_poll_at) => (),
-            Err(smoltcp::Error::Unrecognized) => (),
-            Err(err) => warn!("network error: {}", err)
+        {
+            let sockets = &mut *borrow_mut!(scheduler.sockets());
+            loop {
+                match interface.poll(sockets, board::clock::get_ms()) {
+                    Ok(true) => (),
+                    Ok(false) => break,
+                    Err(smoltcp::Error::Unrecognized) => (),
+                    Err(err) => warn!("network error: {}", err)
+                }
+            }
         }
     }
 }