diff --git a/artiq/firmware/Cargo.lock b/artiq/firmware/Cargo.lock
index 982dffc91..6a8a8f509 100644
--- a/artiq/firmware/Cargo.lock
+++ b/artiq/firmware/Cargo.lock
@@ -97,7 +97,7 @@ dependencies = [
  "fringe 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "logger_artiq 0.0.0",
- "smoltcp 0.2.1 (git+https://github.com/m-labs/smoltcp?rev=ebee5b7)",
+ "smoltcp 0.2.1 (git+https://github.com/m-labs/smoltcp?rev=e8ece3e)",
  "std_artiq 0.0.0",
 ]
 
@@ -116,7 +116,7 @@ dependencies = [
 [[package]]
 name = "smoltcp"
 version = "0.2.1"
-source = "git+https://github.com/m-labs/smoltcp?rev=ebee5b7#ebee5b7b584399ddae91320818f116c6173fc6b4"
+source = "git+https://github.com/m-labs/smoltcp?rev=e8ece3e#e8ece3e56775f38b41906c442db320c980b98c94"
 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)",
@@ -150,7 +150,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "ab83497bf8bf4ed2a74259c1c802351fcd67a65baa86394b6ba73c36f4838054"
 "checksum log_buffer 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ec57723b84bbe7bdf76aa93169c9b59e67473317c6de3a83cb2a0f8ccb2aa493"
 "checksum managed 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "5981b4c6de5ce272aaf2caaa56adb8f6fd24a73206b38302db572ab9374aab10"
-"checksum smoltcp 0.2.1 (git+https://github.com/m-labs/smoltcp?rev=ebee5b7)" = "<none>"
+"checksum smoltcp 0.2.1 (git+https://github.com/m-labs/smoltcp?rev=e8ece3e)" = "<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 b403299fa..7ca898910 100644
--- a/artiq/firmware/runtime/Cargo.toml
+++ b/artiq/firmware/runtime/Cargo.toml
@@ -23,6 +23,6 @@ byteorder = { version = "1.0", default-features = false }
 
 [dependencies.smoltcp]
 git = "https://github.com/m-labs/smoltcp"
-rev = "ebee5b7"
+rev = "e8ece3e"
 default-features = false
 features = ["use_alloc", "use_collections", "use_log"]#, "verbose"]