diff --git a/Cargo.lock b/Cargo.lock
index f1d09d3248..e12d606f91 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -472,9 +472,9 @@ checksum = "3c5e1a9a646d36c3599cd173a41282daf47c44583ad367b8e6837255952e5c67"
 
 [[package]]
 name = "smoltcp"
-version = "0.11.0"
+version = "0.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5a1a996951e50b5971a2c8c0fa05a381480d70a933064245c4a223ddc87ccc97"
+checksum = "dad095989c1533c1c266d9b1e8d70a1329dd3723c3edac6d03bbd67e7bf6f4bb"
 dependencies = [
  "bitflags 1.3.2",
  "byteorder 1.5.0",
diff --git a/Cargo.toml b/Cargo.toml
index 73e9390b05..24da1df44b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -32,7 +32,7 @@ default-features = false
 features = ["release_max_level_warn"]
 
 [dependencies.smoltcp]
-version = "0.11.0"
+version = "0.12.0"
 default-features = false
 features = [
     "std",
diff --git a/src/smolnetd/link/ethernet.rs b/src/smolnetd/link/ethernet.rs
index 58dfab3d13..5f32a479dd 100644
--- a/src/smolnetd/link/ethernet.rs
+++ b/src/smolnetd/link/ethernet.rs
@@ -137,7 +137,11 @@ impl EthernetLink {
                     return;
                 }
 
-                if !source_hardware_addr.is_unicast() || !source_protocol_addr.is_unicast() {
+                if !source_hardware_addr.is_unicast()
+                    || source_protocol_addr.is_broadcast()
+                    || source_protocol_addr.is_multicast()
+                    || source_protocol_addr.is_unspecified()
+                {
                     return;
                 }
 
diff --git a/src/smolnetd/router/mod.rs b/src/smolnetd/router/mod.rs
index 40a360ecf0..3cfd0a2fea 100644
--- a/src/smolnetd/router/mod.rs
+++ b/src/smolnetd/router/mod.rs
@@ -178,7 +178,7 @@ pub struct RxToken<'a> {
 impl<'a> smoltcp::phy::RxToken for RxToken<'a> {
     fn consume<R, F>(self, f: F) -> R
     where
-        F: FnOnce(&mut [u8]) -> R,
+        F: FnOnce(&[u8]) -> R,
     {
         let ((), buf) = self
             .rx_buffer
diff --git a/src/smolnetd/scheme/netcfg/mod.rs b/src/smolnetd/scheme/netcfg/mod.rs
index 95492838ef..846bcddfdb 100644
--- a/src/smolnetd/scheme/netcfg/mod.rs
+++ b/src/smolnetd/scheme/netcfg/mod.rs
@@ -82,7 +82,7 @@ fn mk_root_node(
                     if cur_value.is_none() {
                         let ip = Ipv4Address::from_str(line.trim())
                             .map_err(|_| SyscallError::new(syscall::EINVAL))?;
-                        if !ip.is_unicast() {
+                        if ip.is_broadcast() || ip.is_multicast() || ip.is_unspecified() {
                             return Err(SyscallError::new(syscall::EINVAL));
                         }
                         *cur_value = Some(ip);