diff --git a/src/compile.rs b/src/compile.rs
index 8d8bff27..b0a489f2 100644
--- a/src/compile.rs
+++ b/src/compile.rs
@@ -2,11 +2,9 @@ mod include_files;
 
 pub use include_files::*;
 
-use std::{
-  collections::{BTreeMap, BTreeSet},
-  fmt::Write,
-  hash::{DefaultHasher, Hasher},
-};
+use alloc::collections::{BTreeMap, BTreeSet};
+use core::{fmt::Write, hash::Hasher};
+use std::hash::DefaultHasher;
 
 use crate::prelude::*;
 use hvm64_host::Host;
diff --git a/src/main.rs b/src/main.rs
index cd7c30e4..14a6d53f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,13 +5,19 @@ mod compile;
 mod args;
 mod full;
 
+use crate::prelude::*;
+
+use core::time::Duration;
 use std::{
-  env::consts::{DLL_PREFIX, DLL_SUFFIX},
+  env::{
+    self,
+    consts::{DLL_PREFIX, DLL_SUFFIX},
+  },
   ffi::OsStr,
   fs, io,
   path::PathBuf,
   process::{self, Stdio},
-  time::{Duration, Instant},
+  time::Instant,
 };
 
 use self::full::{CliMode, FullCli};
@@ -21,12 +27,13 @@ use clap::Parser;
 
 use hvm64_ast::{Book, Net, Tree};
 use hvm64_host::Host;
-use hvm64_runtime::{DynDef, Heap, Port, Trg};
+use hvm64_runtime::{trace, DynDef, Heap, Port, Trg};
 use hvm64_transform::Transform;
+use hvm64_util::pretty_num;
 
 fn main() {
   if cfg!(feature = "trace") {
-    hvm64_runtime::trace::set_hook();
+    trace::set_hook();
   }
 
   let cli = FullCli::parse();
@@ -70,7 +77,7 @@ fn main() {
   };
 
   if cfg!(feature = "trace") {
-    hvm64_runtime::trace::_read_traces(usize::MAX);
+    trace::_read_traces(usize::MAX);
   }
 }
 
@@ -124,7 +131,7 @@ fn load_book(files: &[PathBuf], transform_args: TransformArgs) -> Book {
 }
 
 fn load_dylibs(host: &mut Host, include: &[PathBuf]) {
-  let current_dir = std::env::current_dir().unwrap();
+  let current_dir = env::current_dir().unwrap();
 
   for file in include {
     unsafe {
@@ -163,7 +170,7 @@ fn load_dylibs(host: &mut Host, include: &[PathBuf]) {
       });
 
       // Leak the lib to avoid unloading it, as code from it is still referenced.
-      std::mem::forget(lib);
+      mem::forget(lib);
     }
   }
 }
@@ -198,17 +205,6 @@ fn print_stats(net: &hvm64_runtime::Net, elapsed: Duration) {
   eprintln!("RPS    : {:.3} M", (net.rwts.total() as f64) / (elapsed.as_millis() as f64) / 1000.0);
 }
 
-fn pretty_num(n: u64) -> String {
-  n.to_string()
-    .as_bytes()
-    .rchunks(3)
-    .rev()
-    .map(|x| std::str::from_utf8(x).unwrap())
-    .flat_map(|x| ["_", x])
-    .skip(1)
-    .collect()
-}
-
 /// Compiles the `.hvm` directory, appending the provided `args` to `cargo`.
 fn compile_temp_hvm() -> Result<(), io::Error> {
   let output = process::Command::new("cargo")
diff --git a/tests/cli.rs b/tests/cli.rs
index 58cdacb3..e166ef1f 100644
--- a/tests/cli.rs
+++ b/tests/cli.rs
@@ -2,6 +2,7 @@
 
 use std::{
   error::Error,
+  fs,
   io::Read,
   process::{Command, ExitStatus, Stdio},
 };
@@ -253,5 +254,5 @@ fn test_cli_compile() {
   [#13 #1]
   "###);
 
-  std::fs::remove_file("examples/arithmetic").unwrap();
+  fs::remove_file("examples/arithmetic").unwrap();
 }
diff --git a/tests/tests.rs b/tests/tests.rs
index 5f024f3f..2141f71a 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -1,6 +1,7 @@
+use core::str::FromStr;
 use dyntest::{dyntest, DynTester};
 use hvm64_transform::pre_reduce::PreReduce;
-use std::{fs, path::Path, str::FromStr};
+use std::{fs, path::Path};
 
 use hvm64_ast::{self as ast, Book, Net};
 use hvm64_host::Host;
diff --git a/tests/transform.rs b/tests/transform.rs
index 30794c90..66b015f8 100644
--- a/tests/transform.rs
+++ b/tests/transform.rs
@@ -6,7 +6,7 @@ use hvm64_ast::{Book, Net};
 use hvm64_transform::{eta_reduce::EtaReduce, inline::Inline, pre_reduce::PreReduce, prune::Prune, TransformError};
 
 use insta::assert_snapshot;
-use std::str::FromStr;
+use core::str::FromStr;
 
 mod loaders;
 use loaders::*;