diff --git a/artiq/firmware/libboard_misoc/net_settings.rs b/artiq/firmware/libboard_misoc/net_settings.rs
index 20b204c80..466e1a893 100644
--- a/artiq/firmware/libboard_misoc/net_settings.rs
+++ b/artiq/firmware/libboard_misoc/net_settings.rs
@@ -1,21 +1,14 @@
 use core::fmt;
 use core::fmt::{Display, Formatter};
 use core::str::FromStr;
-use smoltcp::iface::{Interface, InterfaceBuilder};
-use smoltcp::phy::Device;
 
-use smoltcp::wire::{EthernetAddress, IpAddress, IpCidr, Ipv4Address, Ipv4Cidr};
+use smoltcp::wire::{EthernetAddress, IpAddress, Ipv4Address};
 
 use config;
 #[cfg(soc_platform = "kasli")]
 use i2c_eeprom;
 
 
-const IPV4_INDEX: usize = 0;
-const IPV6_LL_INDEX: usize = 1;
-const IPV6_INDEX: usize = 2;
-const IP_ADDRESS_STORAGE_SIZE: usize = 3;
-
 pub enum Ipv4AddrConfig {
     UseDhcp,
     Static(Ipv4Address),
@@ -109,33 +102,3 @@ pub fn get_adresses() -> NetAddresses {
         ipv6_addr: ipv6_addr
     }
 }
-
-pub trait InterfaceBuilderEx {
-    fn init_ip_addrs(self, net_addresses: &NetAddresses) -> Self;
-}
-
-impl<'a, DeviceT: for<'d> Device<'d>> InterfaceBuilderEx for InterfaceBuilder<'a, DeviceT> {
-    fn init_ip_addrs(self, net_addresses: &NetAddresses) -> Self {
-        let mut storage = [
-            IpCidr::new(IpAddress::Ipv4(Ipv4Address::UNSPECIFIED), 0);  IP_ADDRESS_STORAGE_SIZE
-        ];
-        if let Ipv4AddrConfig::Static(ipv4) = net_addresses.ipv4_addr {
-            storage[IPV4_INDEX] = IpCidr::new(IpAddress::Ipv4(ipv4), 0);
-        }
-        storage[IPV6_LL_INDEX] = IpCidr::new(net_addresses.ipv6_ll_addr, 0);
-        if let Some(ipv6) = net_addresses.ipv6_addr {
-            storage[IPV6_INDEX] = IpCidr::new(ipv6, 0);
-        }
-        self.ip_addrs(storage)
-    }
-}
-
-pub trait InterfaceEx {
-    fn update_ipv4_addr(&mut self, addr: &Ipv4Cidr);
-}
-
-impl<'a, DeviceT: for<'d> Device<'d>> InterfaceEx for Interface<'a, DeviceT> {
-    fn update_ipv4_addr(&mut self, addr: &Ipv4Cidr) {
-        self.update_ip_addrs(|storage| storage[IPV4_INDEX] = IpCidr::Ipv4(*addr))
-    }
-}
diff --git a/artiq/firmware/runtime/main.rs b/artiq/firmware/runtime/main.rs
index f1e7e7108..01cf89f5c 100644
--- a/artiq/firmware/runtime/main.rs
+++ b/artiq/firmware/runtime/main.rs
@@ -27,12 +27,12 @@ extern crate riscv;
 
 use core::cell::RefCell;
 use core::convert::TryFrom;
-use smoltcp::wire::HardwareAddress;
+use smoltcp::wire::{HardwareAddress, IpAddress, IpCidr, Ipv4Address};
 
 use board_misoc::{csr, ident, clock, spiflash, config, net_settings, pmp, boot};
 #[cfg(has_ethmac)]
 use board_misoc::ethmac;
-use board_misoc::net_settings::{Ipv4AddrConfig, InterfaceBuilderEx};
+use board_misoc::net_settings::{NetAddresses, Ipv4AddrConfig};
 #[cfg(has_drtio)]
 use board_artiq::drtioaux;
 use board_artiq::drtio_routing;
@@ -61,6 +61,13 @@ mod moninj;
 mod analyzer;
 mod dhcp;
 
+// Fixed indexes for the IP addresses so that they can be modified with some
+// semblance of confidence
+pub const IPV4_INDEX: usize = 0;
+pub const IPV6_LL_INDEX: usize = 1;
+pub const IPV6_INDEX: usize = 2;
+const IP_ADDRESS_STORAGE_SIZE: usize = 3;
+
 #[cfg(has_grabber)]
 fn grabber_thread(io: sched::Io) {
     loop {
@@ -89,6 +96,20 @@ fn setup_log_levels() {
     }
 }
 
+pub fn get_ip_addrs(net_addresses: &NetAddresses) -> [IpCidr; IP_ADDRESS_STORAGE_SIZE] {
+    let mut storage = [
+        IpCidr::new(IpAddress::Ipv4(Ipv4Address::UNSPECIFIED), 0);  IP_ADDRESS_STORAGE_SIZE
+    ];
+    if let Ipv4AddrConfig::Static(ipv4) = net_addresses.ipv4_addr {
+        storage[IPV4_INDEX] = IpCidr::new(IpAddress::Ipv4(ipv4), 0);
+    }
+    storage[IPV6_LL_INDEX] = IpCidr::new(net_addresses.ipv6_ll_addr, 0);
+    if let Some(ipv6) = net_addresses.ipv6_addr {
+        storage[IPV6_INDEX] = IpCidr::new(ipv6, 0);
+    }
+    storage
+}
+
 fn startup() {
     clock::init();
     info!("ARTIQ runtime starting...");
@@ -151,7 +172,7 @@ fn startup() {
     };
     let interface = smoltcp::iface::InterfaceBuilder::new(net_device, vec![])
         .hardware_addr(HardwareAddress::Ethernet(net_addresses.hardware_addr))
-        .init_ip_addrs(&net_addresses)
+        .ip_addrs(get_ip_addrs(&net_addresses))
         .neighbor_cache(neighbor_cache)
         .finalize();
 
diff --git a/artiq/firmware/runtime/sched.rs b/artiq/firmware/runtime/sched.rs
index a31c6ec43..860ec5347 100644
--- a/artiq/firmware/runtime/sched.rs
+++ b/artiq/firmware/runtime/sched.rs
@@ -8,7 +8,7 @@ use fringe::OwnedStack;
 use fringe::generator::{Generator, Yielder, State as GeneratorState};
 use smoltcp::time::Duration;
 use smoltcp::Error as NetworkError;
-use smoltcp::wire::{IpEndpoint, Ipv4Cidr};
+use smoltcp::wire::{IpEndpoint, Ipv4Cidr, IpCidr};
 use smoltcp::iface::{Interface, SocketHandle};
 
 use io::{Read, Write};
@@ -16,7 +16,7 @@ use board_misoc::clock;
 use urc::Urc;
 use board_misoc::ethmac::EthernetDevice;
 use smoltcp::phy::Tracer;
-use board_misoc::net_settings::InterfaceEx;
+use IPV4_INDEX;
 
 #[derive(Fail, Debug)]
 pub enum Error {
@@ -276,7 +276,9 @@ impl<'a> Io<'a> {
     }
 
     pub fn set_ipv4_address(&self, addr: &Ipv4Cidr) {
-        self.network.borrow_mut().update_ipv4_addr(addr)
+        self.network.borrow_mut().update_ip_addrs(|addrs| {
+            addrs.as_mut()[IPV4_INDEX] = IpCidr::Ipv4(*addr);
+        })
     }
 }