diff --git a/hitl/run.sh b/hitl/run.sh
index 41d59a0..2af4732 100755
--- a/hitl/run.sh
+++ b/hitl/run.sh
@@ -27,6 +27,6 @@ sleep 30
 ping -c 5 -w 20 stabilizer-hitl
 
 # Test the MQTT interface.
-python3 miniconf.py dt/sinara/stabilizer afe/0='"G2"'
-python3 miniconf.py dt/sinara/stabilizer afe/0='"G1"' iir_ch/0/0=\
+python3 miniconf.py dt/sinara/dual-iir/04-91-62-d9-7e-5f afe/0='"G2"'
+python3 miniconf.py dt/sinara/dual-iir/04-91-62-d9-7e-5f afe/0='"G1"' iir_ch/0/0=\
 '{"y_min": -32767, "y_max": 32767, "y_offset": 0, "ba": [1.0, 0, 0, 0, 0]}'
diff --git a/src/bin/dual-iir.rs b/src/bin/dual-iir.rs
index 8f07cf1..eaa82ae 100644
--- a/src/bin/dual-iir.rs
+++ b/src/bin/dual-iir.rs
@@ -62,7 +62,10 @@ const APP: () = {
         let mqtt_config = MiniconfInterface::new(
             stabilizer.net.stack,
             "",
-            "dt/sinara/stabilizer",
+            &net::get_device_prefix(
+                env!("CARGO_BIN_NAME"),
+                stabilizer.net.mac_address,
+            ),
             stabilizer.net.phy,
             stabilizer.cycle_counter,
         );
diff --git a/src/bin/lockin-external.rs b/src/bin/lockin-external.rs
index 36bd882..082b0d2 100644
--- a/src/bin/lockin-external.rs
+++ b/src/bin/lockin-external.rs
@@ -8,6 +8,8 @@ use serde::Deserialize;
 
 use dsp::{Accu, Complex, ComplexExt, Lockin, RPLL};
 
+use stabilizer::net;
+
 use stabilizer::hardware::{
     design_parameters, setup, Adc0Input, Adc1Input, AfeGain, Dac0Output,
     Dac1Output, InputStamper, AFE0, AFE1,
@@ -74,7 +76,10 @@ const APP: () = {
         let mqtt_config = MiniconfInterface::new(
             stabilizer.net.stack,
             "",
-            "dt/sinara/lockin",
+            &net::get_device_prefix(
+                env!("CARGO_BIN_NAME"),
+                stabilizer.net.mac_address,
+            ),
             stabilizer.net.phy,
             stabilizer.cycle_counter,
         );
diff --git a/src/hardware/configuration.rs b/src/hardware/configuration.rs
index 5bc5a20..f453c11 100644
--- a/src/hardware/configuration.rs
+++ b/src/hardware/configuration.rs
@@ -57,6 +57,7 @@ impl NetStorage {
 pub struct NetworkDevices {
     pub stack: NetworkStack,
     pub phy: EthernetPhy,
+    pub mac_address: smoltcp::wire::EthernetAddress,
 }
 
 /// The available hardware interfaces on Stabilizer.
@@ -618,6 +619,7 @@ pub fn setup(
         NetworkDevices {
             stack,
             phy: lan8742a,
+            mac_address: mac_addr,
         }
     };
 
diff --git a/src/net/mod.rs b/src/net/mod.rs
index 23d712d..13b514c 100644
--- a/src/net/mod.rs
+++ b/src/net/mod.rs
@@ -2,6 +2,9 @@ use crate::hardware::{
     design_parameters::MQTT_BROKER, CycleCounter, EthernetPhy, NetworkStack,
 };
 
+use core::fmt::Write;
+
+use heapless::{consts, String};
 use miniconf::minimq;
 
 /// Potential actions for firmware to take.
@@ -107,3 +110,39 @@ where
         }
     }
 }
+
+/// Get the MQTT prefix of a device.
+///
+/// # Args
+/// * `app` - The name of the application that is executing.
+/// * `mac` - The ethernet MAC address of the device.
+///
+/// # Returns
+/// The MQTT prefix used for this device.
+pub fn get_device_prefix(
+    app: &str,
+    mac: smoltcp_nal::smoltcp::wire::EthernetAddress,
+) -> String<consts::U128> {
+    let mac_string = {
+        let mut mac_string: String<consts::U32> = String::new();
+        let mac = mac.as_bytes();
+
+        // Note(unwrap): 32-bytes is guaranteed to be valid for any mac address, as the address has
+        // a fixed length.
+        write!(
+            &mut mac_string,
+            "{:02x}-{:02x}-{:02x}-{:02x}-{:02x}-{:02x}",
+            mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]
+        )
+        .unwrap();
+
+        mac_string
+    };
+
+    // Note(unwrap): The mac address + binary name must be short enough to fit into this string. If
+    // they are defined too long, this will panic and the device will fail to boot.
+    let mut prefix: String<consts::U128> = String::new();
+    write!(&mut prefix, "dt/sinara/{}/{}", app, mac_string).unwrap();
+
+    prefix
+}