diff --git a/hblang/src/codegen.rs b/hblang/src/codegen.rs
index 34e6d479..95502f18 100644
--- a/hblang/src/codegen.rs
+++ b/hblang/src/codegen.rs
@@ -3205,7 +3205,10 @@ impl Codegen {
 
             #[cfg(test)]
             {
-                self.disasm(&mut String::new());
+                let mut vc = Vec::<u8>::new();
+                if self.disasm(&mut vc).is_err() {
+                    panic!("{}", String::from_utf8(vc).unwrap());
+                }
             }
 
             self.run_vm();
@@ -3223,8 +3226,7 @@ impl Codegen {
         ret
     }
 
-    #[cfg(test)]
-    fn disasm(&mut self, output: &mut String) {
+    pub fn disasm(&mut self, output: &mut impl std::io::Write) -> std::io::Result<()> {
         use crate::DisasmItem;
         let mut sluce = self.output.code.as_slice();
         let functions = self
@@ -3280,20 +3282,15 @@ impl Codegen {
                     .map(|s| (s.range.start, ("string", s.range.len() as _, DisasmItem::Global))),
             )
             .collect::<HashMap<_, _>>();
-        if crate::disasm(&mut sluce, &functions, output, |bin| {
+        crate::disasm(&mut sluce, &functions, output, |bin| {
             if self.ct.active()
                 && let Some(trap) = Self::read_trap(bin.as_ptr() as u64)
             {
                 bin.take(..trap.size() + 1).unwrap();
             }
         })
-        .is_err()
-        {
-            panic!("{} {:?}", output, sluce);
-        }
     }
 
-    #[cfg(test)]
     fn is_fully_linked(&self, func: ty::Func) -> bool {
         self.output
             .relocs
@@ -3471,7 +3468,12 @@ mod tests {
         let mut out = Vec::new();
         codegen.dump(&mut out).unwrap();
 
-        codegen.disasm(output);
+        let mut buf = Vec::<u8>::new();
+        let err = codegen.disasm(&mut buf);
+        output.push_str(String::from_utf8(buf).unwrap().as_str());
+        if err.is_err() {
+            return;
+        }
 
         use std::fmt::Write;
 
diff --git a/hblang/src/lib.rs b/hblang/src/lib.rs
index 8cef29bd..69a7e6ad 100644
--- a/hblang/src/lib.rs
+++ b/hblang/src/lib.rs
@@ -135,27 +135,25 @@ fn decode<T>(binary: &mut &[u8]) -> Option<T> {
     unsafe { Some(std::ptr::read(binary.take(..std::mem::size_of::<T>())?.as_ptr() as *const T)) }
 }
 
-#[cfg(test)]
 #[derive(Clone, Copy)]
 enum DisasmItem {
     Func,
     Global,
 }
 
-#[cfg(test)]
 fn disasm(
     binary: &mut &[u8],
     functions: &HashMap<u32, (&str, u32, DisasmItem)>,
-    out: &mut String,
+    out: &mut impl std::io::Write,
     mut eca_handler: impl FnMut(&mut &[u8]),
-) -> std::fmt::Result {
+) -> std::io::Result<()> {
     use self::instrs::Instr;
 
-    fn instr_from_byte(b: u8) -> Result<Instr, std::fmt::Error> {
+    fn instr_from_byte(b: u8) -> std::io::Result<Instr> {
         if b as usize >= instrs::NAMES.len() {
-            return Err(std::fmt::Error);
+            return Err(std::io::ErrorKind::InvalidData.into());
         }
-        unsafe { std::mem::transmute(b) }
+        Ok(unsafe { std::mem::transmute::<u8, Instr>(b) })
     }
 
     let mut labels = HashMap::<u32, u32>::default();
@@ -179,7 +177,7 @@ fn disasm(
             if offset as u32 == off + len {
                 break;
             }
-            instrs::parse_args(binary, inst, &mut buf).ok_or(std::fmt::Error)?;
+            instrs::parse_args(binary, inst, &mut buf).ok_or(std::io::ErrorKind::OutOfMemory)?;
 
             for op in buf.drain(..) {
                 let rel = match op {
@@ -211,18 +209,16 @@ fn disasm(
         }
         let prev = *binary;
 
-        use std::fmt::Write;
-
         writeln!(out, "{name}:")?;
 
         binary.take(..off as usize).unwrap();
         while let Some(&byte) = binary.first() {
-            let inst = instr_from_byte(byte)?;
+            let inst = instr_from_byte(byte).unwrap();
             let offset: i32 = (prev.len() - binary.len()).try_into().unwrap();
             if offset as u32 == off + len {
                 break;
             }
-            instrs::parse_args(binary, inst, &mut buf).ok_or(std::fmt::Error)?;
+            instrs::parse_args(binary, inst, &mut buf).unwrap();
 
             if let Some(label) = labels.get(&offset.try_into().unwrap()) {
                 write!(out, "{:>2}: ", label)?;
@@ -281,8 +277,12 @@ fn disasm(
         *binary = prev;
     }
 
-    if has_oob || has_cycle {
-        return Err(std::fmt::Error);
+    if has_oob {
+        return Err(std::io::ErrorKind::InvalidInput.into());
+    }
+
+    if has_cycle {
+        return Err(std::io::ErrorKind::TimedOut.into());
     }
 
     Ok(())
@@ -700,6 +700,7 @@ pub fn run_test(
 pub struct Options {
     pub fmt: bool,
     pub fmt_current: bool,
+    pub dump_asm: bool,
     pub extra_threads: usize,
 }
 
@@ -752,13 +753,17 @@ pub fn run_compiler(
     } else if options.fmt_current {
         let ast = parsed.into_iter().next().unwrap();
         let source = std::fs::read_to_string(&*ast.path)?;
-        format_to(&ast, &source, &mut std::io::stdout())?;
+        format_to(&ast, &source, out)?;
     } else {
         let mut codegen = codegen::Codegen::default();
         codegen.files = parsed;
 
         codegen.generate();
-        codegen.dump(out)?;
+        if options.dump_asm {
+            codegen.disasm(out)?;
+        } else {
+            codegen.dump(out)?;
+        }
     }
 
     Ok(())
diff --git a/hblang/src/main.rs b/hblang/src/main.rs
index 6065f66d..c1e0386e 100644
--- a/hblang/src/main.rs
+++ b/hblang/src/main.rs
@@ -15,6 +15,7 @@ fn main() -> std::io::Result<()> {
         hblang::Options {
             fmt: args.contains(&"--fmt"),
             fmt_current: args.contains(&"--fmt-current"),
+            dump_asm: args.contains(&"--dump-asm"),
             extra_threads: args
                 .iter()
                 .position(|&a| a == "--threads")
diff --git a/hblang/src/son.rs b/hblang/src/son.rs
index 60b40ce2..4ec22575 100644
--- a/hblang/src/son.rs
+++ b/hblang/src/son.rs
@@ -7,7 +7,7 @@ use {
         log,
         parser::{
             self,
-            idfl::{self, index},
+            idfl::{self},
             Expr, ExprRef, FileId, Pos,
         },
         HashMap,
@@ -17,7 +17,6 @@ use {
         mem,
         ops::{self, Range},
         rc::Rc,
-        usize,
     },
 };