diff --git a/crates/private/tests/root-task/ring-test-harness/src/lib.rs b/crates/private/tests/root-task/ring-test-harness/src/lib.rs
index a6415ff4a..7f4bb1da5 100644
--- a/crates/private/tests/root-task/ring-test-harness/src/lib.rs
+++ b/crates/private/tests/root-task/ring-test-harness/src/lib.rs
@@ -9,11 +9,6 @@
 #![feature(cfg_target_thread_local)]
 #![feature(thread_local)]
 
-use core::cell::RefCell;
-
-use rand::rngs::SmallRng;
-use rand::{RngCore, SeedableRng};
-
 use sel4_newlib as _;
 use sel4_root_task::root_task;
 use sel4_test_harness::run_test_main;
@@ -24,35 +19,45 @@ const HEAP_SIZE: usize = 256 * 1024 * 1024;
 
 #[root_task(heap_size = HEAP_SIZE)]
 fn main(_bootinfo: &sel4::BootInfo) -> ! {
-    seed_insecure_dummy_rng(0);
+    init();
     run_test_main();
     sel4::BootInfo::init_thread_tcb().tcb_suspend().unwrap();
     unreachable!()
 }
 
-#[cfg(not(target_thread_local))]
-compile_error!("");
+fn init() {
+    dummy_custom_getrandom::seed_dummy_custom_getrandom(0);
+}
+
+mod dummy_custom_getrandom {
+    use core::cell::RefCell;
 
-#[thread_local]
-static RNG: RefCell<Option<SmallRng>> = RefCell::new(None);
+    use rand::rngs::SmallRng;
+    use rand::{RngCore, SeedableRng};
 
-pub fn seed_insecure_dummy_rng(seed: u64) {
-    assert!(RNG.replace(Some(SmallRng::seed_from_u64(seed))).is_none());
-}
+    #[cfg(not(target_thread_local))]
+    compile_error!("");
+
+    #[thread_local]
+    static RNG: RefCell<Option<SmallRng>> = RefCell::new(None);
 
-pub fn insecure_dummy_rng(buf: &mut [u8]) -> Result<(), getrandom::Error> {
-    if 1_u32.swap_bytes() == 0 {
-        panic!()
+    pub(crate) fn seed_dummy_custom_getrandom(seed: u64) {
+        assert!(RNG.replace(Some(SmallRng::seed_from_u64(seed))).is_none());
     }
-    RNG.borrow_mut().as_mut().unwrap().fill_bytes(buf);
-    Ok(())
-}
 
-getrandom::register_custom_getrandom!(insecure_dummy_rng);
+    fn dummy_custom_getrandom(buf: &mut [u8]) -> Result<(), getrandom::Error> {
+        RNG.borrow_mut().as_mut().unwrap().fill_bytes(buf);
+        Ok(())
+    }
 
-// https://github.com/rust-lang/compiler-builtins/pull/563
-#[cfg(any(target_arch = "riscv32", target_arch = "riscv64"))]
-#[no_mangle]
-pub extern "C" fn __bswapsi2(u: u32) -> u32 {
-    u.swap_bytes()
+    getrandom::register_custom_getrandom!(dummy_custom_getrandom);
+}
+
+mod compiler_builtins_supplement {
+    // https://github.com/rust-lang/compiler-builtins/pull/563
+    #[cfg(any(target_arch = "riscv32", target_arch = "riscv64"))]
+    #[no_mangle]
+    pub extern "C" fn __bswapsi2(u: u32) -> u32 {
+        u.swap_bytes()
+    }
 }