diff --git a/Cargo.lock b/Cargo.lock
index 7fa03f0..0999288 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -724,6 +724,7 @@ dependencies = [
  "dsp",
  "embedded-hal",
  "enum-iterator",
+ "generic-array 0.14.4",
  "heapless",
  "log",
  "mcp23017",
diff --git a/Cargo.toml b/Cargo.toml
index 599e595..f384fe9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -46,6 +46,7 @@ dsp = { path = "dsp" }
 ad9959 = { path = "ad9959" }
 smoltcp-nal = "0.1.0"
 miniconf = "0.1"
+generic-array = "0.14"
 
 [patch.crates-io.miniconf]
 git = "https://github.com/quartiq/miniconf.git"
diff --git a/dsp/src/lockin.rs b/dsp/src/lockin.rs
index 6a977b4..613a133 100644
--- a/dsp/src/lockin.rs
+++ b/dsp/src/lockin.rs
@@ -1,12 +1,12 @@
 use super::{Complex, ComplexExt, Lowpass, MulScaled};
-use generic_array::typenum::U2;
+use generic_array::ArrayLength;
 
 #[derive(Clone, Default)]
-pub struct Lockin {
-    state: [Lowpass<U2>; 2],
+pub struct Lockin<N: ArrayLength<i32>> {
+    state: [Lowpass<N>; 2],
 }
 
-impl Lockin {
+impl<N: ArrayLength<i32>> Lockin<N> {
     /// Update the lockin with a sample taken at a given phase.
     pub fn update(&mut self, sample: i32, phase: i32, k: u8) -> Complex<i32> {
         // Get the LO signal for demodulation and mix the sample;
diff --git a/src/bin/lockin-external.rs b/src/bin/lockin-external.rs
index 3b7c6a8..e44c17e 100644
--- a/src/bin/lockin-external.rs
+++ b/src/bin/lockin-external.rs
@@ -2,10 +2,8 @@
 #![no_std]
 #![no_main]
 
-use stm32h7xx_hal as hal;
-
+use generic_array::typenum::U4;
 use stabilizer::{hardware, hardware::design_parameters};
-
 use dsp::{Accu, Complex, ComplexExt, Lockin, RPLL};
 use hardware::{
     Adc0Input, Adc1Input, Dac0Output, Dac1Output, InputStamper, AFE0, AFE1,
@@ -20,7 +18,7 @@ const APP: () = {
 
         timestamper: InputStamper,
         pll: RPLL,
-        lockin: Lockin,
+        lockin: Lockin<U4>,
     }
 
     #[init]
@@ -156,7 +154,7 @@ const APP: () = {
 
     #[task(binds = ETH, priority = 1)]
     fn eth(_: eth::Context) {
-        unsafe { hal::ethernet::interrupt_handler() }
+        unsafe { stm32h7xx_hal::ethernet::interrupt_handler() }
     }
 
     #[task(binds = SPI2, priority = 3)]
diff --git a/src/bin/lockin-internal.rs b/src/bin/lockin-internal.rs
index 1f9df6e..7ea7e1d 100644
--- a/src/bin/lockin-internal.rs
+++ b/src/bin/lockin-internal.rs
@@ -2,6 +2,7 @@
 #![no_std]
 #![no_main]
 
+use generic_array::typenum::U2;
 use dsp::{Accu, Complex, ComplexExt, Lockin};
 use hardware::{Adc1Input, Dac0Output, Dac1Output, AFE0, AFE1};
 use stabilizer::{hardware, hardware::design_parameters};
@@ -20,7 +21,7 @@ const APP: () = {
         adc: Adc1Input,
         dacs: (Dac0Output, Dac1Output),
 
-        lockin: Lockin,
+        lockin: Lockin<U2>,
     }
 
     #[init]