diff --git a/bench/addictive_addition/run.sh b/bench/addictive_addition/run.sh
index b6509a3..fbe3968 100644
--- a/bench/addictive_addition/run.sh
+++ b/bench/addictive_addition/run.sh
@@ -3,7 +3,6 @@ hyperfine \
     --shell none \
     --prepare 'sync' \
     --warmup 5 \
-    --export-markdown results.md \
     '../../target/release/dust addictive_addition.ds' \
     'node addictive_addition.js' \
     'deno addictive_addition.js' \
diff --git a/bench/recursion/recursion.ds b/bench/recursion/recursion.ds
index 6383028..257c310 100644
--- a/bench/recursion/recursion.ds
+++ b/bench/recursion/recursion.ds
@@ -6,4 +6,4 @@ fn decrement(i: int) -> str {
     decrement(i - 1)
 }
 
-decrement(1000)
+write_line(decrement(10_000))
diff --git a/bench/recursion/recursion.js b/bench/recursion/recursion.js
index 964f6c2..f080f1f 100644
--- a/bench/recursion/recursion.js
+++ b/bench/recursion/recursion.js
@@ -6,4 +6,4 @@ function decrement(i) {
   return decrement(i - 1);
 }
 
-decrement(1000);
+console.log(decrement(10_000));
diff --git a/dust-lang/src/native_function/assertion.rs b/dust-lang/src/native_function/assertion.rs
index c0d4b45..7592eee 100644
--- a/dust-lang/src/native_function/assertion.rs
+++ b/dust-lang/src/native_function/assertion.rs
@@ -1,15 +1,9 @@
 use std::{ops::Range, panic};
 
-use crate::{
-    vm::{Record, ThreadSignal},
-    NativeFunctionError,
-};
+use crate::vm::ThreadData;
 
-pub fn panic(
-    record: &mut Record,
-    _: Option<u8>,
-    argument_range: Range<u8>,
-) -> Result<ThreadSignal, NativeFunctionError> {
+pub fn panic(data: &mut ThreadData, _: Option<u8>, argument_range: Range<u8>) -> bool {
+    let record = data.records.last_mut_unchecked();
     let position = record.current_position();
     let mut message = format!("Dust panic at {position}!");
 
diff --git a/dust-lang/src/native_function/io.rs b/dust-lang/src/native_function/io.rs
index 126cf51..5cc0fe3 100644
--- a/dust-lang/src/native_function/io.rs
+++ b/dust-lang/src/native_function/io.rs
@@ -1,93 +1,70 @@
-use std::io::{self, stdin, stdout, Write};
+use std::io::{stdin, stdout, Write};
 use std::ops::Range;
 
-use crate::vm::{get_next_action, Register, ThreadSignal};
-use crate::{vm::Record, ConcreteValue, NativeFunctionError, Value};
+use crate::{
+    vm::{get_next_action, Register, ThreadData},
+    ConcreteValue, Value,
+};
 
 pub fn read_line(
-    record: &mut Record,
+    data: &mut ThreadData,
     destination: Option<u8>,
     _argument_range: Range<u8>,
-) -> Result<ThreadSignal, NativeFunctionError> {
+) -> bool {
+    let record = data.records.last_mut_unchecked();
     let destination = destination.unwrap();
     let mut buffer = String::new();
 
-    match stdin().read_line(&mut buffer) {
-        Ok(_) => {
-            let length = buffer.len();
+    if stdin().read_line(&mut buffer).is_ok() {
+        let length = buffer.len();
 
-            buffer.truncate(length.saturating_sub(1));
+        buffer.truncate(length.saturating_sub(1));
 
-            let register = Register::Value(Value::Concrete(ConcreteValue::string(buffer)));
+        let register = Register::Value(Value::Concrete(ConcreteValue::string(buffer)));
 
-            record.set_register(destination, register);
-        }
-        Err(error) => {
-            return Err(NativeFunctionError::Io {
-                error: error.kind(),
-                position: record.current_position(),
-            })
-        }
+        record.set_register(destination, register);
     }
 
-    let next_action = get_next_action(record);
+    data.next_action = get_next_action(record);
 
-    Ok(ThreadSignal::Continue(next_action))
+    false
 }
 
-pub fn write(
-    record: &mut Record,
-    _destination: Option<u8>,
-    argument_range: Range<u8>,
-) -> Result<ThreadSignal, NativeFunctionError> {
+pub fn write(data: &mut ThreadData, _destination: Option<u8>, argument_range: Range<u8>) -> bool {
+    let record = data.records.last_mut_unchecked();
     let mut stdout = stdout();
 
     for register_index in argument_range {
         if let Some(value) = record.open_register_allow_empty_unchecked(register_index) {
             let string = value.display(record);
-
-            stdout
-                .write(string.as_bytes())
-                .map_err(|io_error| NativeFunctionError::Io {
-                    error: io_error.kind(),
-                    position: record.current_position(),
-                })?;
+            let _ = stdout.write(string.as_bytes());
         }
     }
 
-    stdout.flush().map_err(|io_error| NativeFunctionError::Io {
-        error: io_error.kind(),
-        position: record.current_position(),
-    })?;
+    let _ = stdout.flush();
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    Ok(ThreadSignal::Continue(next_action))
+    false
 }
 
 pub fn write_line(
-    record: &mut Record,
+    data: &mut ThreadData,
     _destination: Option<u8>,
     argument_range: Range<u8>,
-) -> Result<ThreadSignal, NativeFunctionError> {
-    let map_err = |io_error: io::Error| NativeFunctionError::Io {
-        error: io_error.kind(),
-        position: record.current_position(),
-    };
+) -> bool {
+    let record = data.records.last_mut_unchecked();
     let mut stdout = stdout().lock();
 
     for register_index in argument_range {
         if let Some(value) = record.open_register_allow_empty_unchecked(register_index) {
             let string = value.display(record);
-
-            stdout.write(string.as_bytes()).map_err(map_err)?;
-            stdout.write(b"\n").map_err(map_err)?;
+            let _ = stdout.write(string.as_bytes());
+            let _ = stdout.write(b"\n");
         }
     }
 
-    stdout.flush().map_err(map_err)?;
+    let _ = stdout.flush();
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    Ok(ThreadSignal::Continue(next_action))
+    false
 }
diff --git a/dust-lang/src/native_function/mod.rs b/dust-lang/src/native_function/mod.rs
index 1fd5ed4..c7b6c29 100644
--- a/dust-lang/src/native_function/mod.rs
+++ b/dust-lang/src/native_function/mod.rs
@@ -16,10 +16,7 @@ use std::{
 use serde::{Deserialize, Serialize};
 use smallvec::{smallvec, SmallVec};
 
-use crate::{
-    vm::{Record, ThreadSignal},
-    AnnotatedError, FunctionType, Span, Type,
-};
+use crate::{vm::ThreadData, AnnotatedError, FunctionType, Span, Type};
 
 macro_rules! define_native_function {
     ($(($name:ident, $bytes:literal, $str:expr, $type:expr, $function:expr)),*) => {
@@ -36,13 +33,13 @@ macro_rules! define_native_function {
         impl NativeFunction {
             pub fn call(
                 &self,
-                record: &mut Record,
+                data: &mut ThreadData,
                 destination: Option<u8>,
                 argument_range: Range<u8>,
-            ) -> Result<ThreadSignal, NativeFunctionError> {
+            ) -> bool {
                 match self {
                     $(
-                        NativeFunction::$name => $function(record, destination, argument_range),
+                        NativeFunction::$name => $function(data, destination, argument_range),
                     )*
                 }
             }
diff --git a/dust-lang/src/native_function/string.rs b/dust-lang/src/native_function/string.rs
index 38f2b70..525761e 100644
--- a/dust-lang/src/native_function/string.rs
+++ b/dust-lang/src/native_function/string.rs
@@ -1,15 +1,16 @@
 use std::ops::Range;
 
 use crate::{
-    vm::{get_next_action, Record, Register, ThreadSignal},
-    ConcreteValue, NativeFunctionError, Value,
+    vm::{get_next_action, Register, ThreadData},
+    ConcreteValue, Value,
 };
 
 pub fn to_string(
-    record: &mut Record,
+    data: &mut ThreadData,
     destination: Option<u8>,
     argument_range: Range<u8>,
-) -> Result<ThreadSignal, NativeFunctionError> {
+) -> bool {
+    let record = data.records.last_mut_unchecked();
     let argument_value = record.open_register_unchecked(argument_range.start);
     let argument_string = argument_value.display(record);
     let destination = destination.unwrap();
@@ -17,7 +18,7 @@ pub fn to_string(
 
     record.set_register(destination, register);
 
-    let next_action = get_next_action(record);
+    data.next_action = get_next_action(record);
 
-    Ok(ThreadSignal::Continue(next_action))
+    false
 }
diff --git a/dust-lang/src/vm/mod.rs b/dust-lang/src/vm/mod.rs
index e32ff1d..f39ad72 100644
--- a/dust-lang/src/vm/mod.rs
+++ b/dust-lang/src/vm/mod.rs
@@ -16,7 +16,7 @@ pub use record::Record;
 pub(crate) use run_action::get_next_action;
 pub use run_action::RunAction;
 pub use stack::{FunctionCall, Stack};
-pub use thread::{Thread, ThreadSignal};
+pub use thread::{Thread, ThreadData};
 
 use tracing::{span, Level};
 
diff --git a/dust-lang/src/vm/run_action.rs b/dust-lang/src/vm/run_action.rs
index 29eca8b..f636133 100644
--- a/dust-lang/src/vm/run_action.rs
+++ b/dust-lang/src/vm/run_action.rs
@@ -10,7 +10,7 @@ use crate::{
     AbstractList, Argument, ConcreteValue, DustString, Instruction, Type, Value,
 };
 
-use super::{thread::ThreadData, Pointer, Record, Register, ThreadSignal};
+use super::{thread::ThreadData, Pointer, Record, Register};
 
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub struct RunAction {
@@ -27,7 +27,7 @@ impl From<Instruction> for RunAction {
     }
 }
 
-pub type RunnerLogic = fn(Instruction, &mut ThreadData) -> ThreadSignal;
+pub type RunnerLogic = fn(Instruction, &mut ThreadData) -> bool;
 
 pub const RUNNER_LOGIC_TABLE: [RunnerLogic; 25] = [
     point,
@@ -57,15 +57,17 @@ pub const RUNNER_LOGIC_TABLE: [RunnerLogic; 25] = [
     r#return,
 ];
 
-pub(crate) fn get_next_action(record: &Record) -> RunAction {
+pub(crate) fn get_next_action(record: &mut Record) -> RunAction {
     let instruction = record.chunk.instructions[record.ip];
     let operation = instruction.operation();
     let logic = RUNNER_LOGIC_TABLE[operation.0 as usize];
 
+    record.ip += 1;
+
     RunAction { logic, instruction }
 }
 
-pub fn point(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn point(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Point { from, to } = instruction.into();
     let from_register = record.get_register_unchecked(from);
@@ -77,14 +79,12 @@ pub fn point(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
         record.set_register(from, register);
     }
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn close(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn close(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Close { from, to } = instruction.into();
 
@@ -92,14 +92,12 @@ pub fn close(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
         record.set_register(register_index, Register::Empty);
     }
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn load_boolean(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn load_boolean(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let LoadBoolean {
         destination,
@@ -115,14 +113,12 @@ pub fn load_boolean(instruction: Instruction, data: &mut ThreadData) -> ThreadSi
         record.ip += 1;
     }
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn load_constant(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn load_constant(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let LoadConstant {
         destination,
@@ -139,14 +135,12 @@ pub fn load_constant(instruction: Instruction, data: &mut ThreadData) -> ThreadS
         record.ip += 1;
     }
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn load_list(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn load_list(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let LoadList {
         destination,
@@ -183,14 +177,12 @@ pub fn load_list(instruction: Instruction, data: &mut ThreadData) -> ThreadSigna
 
     record.set_register(destination, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn load_function(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn load_function(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let LoadFunction {
         destination,
@@ -202,14 +194,12 @@ pub fn load_function(instruction: Instruction, data: &mut ThreadData) -> ThreadS
 
     record.set_register(destination, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn load_self(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn load_self(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let LoadSelf { destination } = instruction.into();
     let function = record.as_function();
@@ -217,14 +207,12 @@ pub fn load_self(instruction: Instruction, data: &mut ThreadData) -> ThreadSigna
 
     record.set_register(destination, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn get_local(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn get_local(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let GetLocal {
         destination,
@@ -235,14 +223,12 @@ pub fn get_local(instruction: Instruction, data: &mut ThreadData) -> ThreadSigna
 
     record.set_register(destination, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn set_local(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn set_local(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let SetLocal {
         register_index,
@@ -253,14 +239,12 @@ pub fn set_local(instruction: Instruction, data: &mut ThreadData) -> ThreadSigna
 
     record.set_register(local_register_index, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn add(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn add(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Add {
         destination,
@@ -274,14 +258,12 @@ pub fn add(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
 
     record.set_register(destination, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn subtract(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn subtract(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Subtract {
         destination,
@@ -295,14 +277,12 @@ pub fn subtract(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal
 
     record.set_register(destination, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn multiply(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn multiply(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Multiply {
         destination,
@@ -324,14 +304,12 @@ pub fn multiply(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal
 
     record.set_register(destination, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn divide(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn divide(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Divide {
         destination,
@@ -353,14 +331,12 @@ pub fn divide(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
 
     record.set_register(destination, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn modulo(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn modulo(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Modulo {
         destination,
@@ -382,14 +358,12 @@ pub fn modulo(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
 
     record.set_register(destination, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn test(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn test(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Test {
         operand_register,
@@ -406,14 +380,12 @@ pub fn test(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
         record.ip += 1;
     }
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn test_set(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn test_set(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let TestSet {
         destination,
@@ -428,7 +400,6 @@ pub fn test_set(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal
     };
 
     if boolean == test_value {
-        record.ip += 1;
     } else {
         let pointer = match argument {
             Argument::Constant(constant_index) => Pointer::Constant(constant_index),
@@ -439,14 +410,12 @@ pub fn test_set(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal
         record.set_register(destination, register);
     }
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn equal(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn equal(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Equal { value, left, right } = instruction.into();
     let left = record.get_argument_unchecked(left);
@@ -457,14 +426,12 @@ pub fn equal(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
         record.ip += 1;
     }
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn less(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn less(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Less { value, left, right } = instruction.into();
     let left = record.get_argument_unchecked(left);
@@ -475,14 +442,12 @@ pub fn less(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
         record.ip += 1;
     }
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn less_equal(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn less_equal(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let LessEqual { value, left, right } = instruction.into();
     let left = record.get_argument_unchecked(left);
@@ -493,14 +458,12 @@ pub fn less_equal(instruction: Instruction, data: &mut ThreadData) -> ThreadSign
         record.ip += 1;
     }
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn negate(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn negate(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Negate {
         destination,
@@ -512,14 +475,12 @@ pub fn negate(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
 
     record.set_register(destination, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn not(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn not(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Not {
         destination,
@@ -534,14 +495,12 @@ pub fn not(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
 
     record.set_register(destination, register);
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn jump(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn jump(instruction: Instruction, data: &mut ThreadData) -> bool {
     let record = data.records.last_mut_unchecked();
     let Jump {
         offset,
@@ -555,22 +514,19 @@ pub fn jump(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
         record.ip -= offset + 1;
     }
 
-    record.ip += 1;
+    data.next_action = get_next_action(record);
 
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn call(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
-    let mut current_record = data.records.pop_unchecked();
+pub fn call(instruction: Instruction, data: &mut ThreadData) -> bool {
+    let current_record = data.records.pop_unchecked();
     let Call {
         destination: return_register,
         function_register,
         argument_count,
         is_recursive,
     } = instruction.into();
-
     let function = current_record
         .open_register_unchecked(function_register)
         .as_function()
@@ -602,19 +558,16 @@ pub fn call(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
         next_record.set_register(argument_index as u8, Register::Value(argument));
     }
 
-    let next_action = get_next_action(&next_record);
-
-    current_record.ip += 1;
+    data.next_action = get_next_action(&mut next_record);
 
     data.call_stack.push(next_call);
     data.records.push(current_record);
     data.records.push(next_record);
 
-    ThreadSignal::Continue(next_action)
+    false
 }
 
-pub fn call_native(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
-    let record = data.records.last_mut_unchecked();
+pub fn call_native(instruction: Instruction, data: &mut ThreadData) -> bool {
     let CallNative {
         destination,
         function,
@@ -623,18 +576,10 @@ pub fn call_native(instruction: Instruction, data: &mut ThreadData) -> ThreadSig
     let first_argument_index = destination - argument_count;
     let argument_range = first_argument_index..destination;
 
-    function
-        .call(record, Some(destination), argument_range)
-        .unwrap_or_else(|error| panic!("{error:?}"));
-
-    record.ip += 1;
-
-    let next_action = get_next_action(record);
-
-    ThreadSignal::Continue(next_action)
+    function.call(data, Some(destination), argument_range)
 }
 
-pub fn r#return(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal {
+pub fn r#return(instruction: Instruction, data: &mut ThreadData) -> bool {
     trace!("Returning with call stack:\n{}", data.call_stack);
 
     let Return {
@@ -642,29 +587,29 @@ pub fn r#return(instruction: Instruction, data: &mut ThreadData) -> ThreadSignal
         return_register,
     } = instruction.into();
     let current_call = data.call_stack.pop_unchecked();
-    let mut current_record = data.records.pop_unchecked();
+    let mut current_record = if data.call_stack.is_empty() {
+        if should_return_value {
+            data.return_value_index = Some(return_register);
+        };
 
-    let return_value = if should_return_value {
-        Some(current_record.empty_register_or_clone_constant_unchecked(return_register))
+        return true;
     } else {
-        None
+        data.records.pop_unchecked()
     };
 
+    let outer_record = data.records.last_mut_unchecked();
     let destination = current_call.return_register;
 
-    if data.call_stack.is_empty() {
-        return ThreadSignal::End(return_value);
-    }
-
-    let outer_record = data.records.last_mut_unchecked();
-
     if should_return_value {
-        outer_record.set_register(destination, Register::Value(return_value.unwrap()));
+        let return_value =
+            current_record.empty_register_or_clone_constant_unchecked(return_register);
+
+        outer_record.set_register(destination, Register::Value(return_value));
     }
 
-    let next_action = get_next_action(outer_record);
+    data.next_action = get_next_action(outer_record);
 
-    ThreadSignal::Continue(next_action)
+    false
 }
 
 #[cfg(test)]
diff --git a/dust-lang/src/vm/thread.rs b/dust-lang/src/vm/thread.rs
index 66c1e75..3adaaa2 100644
--- a/dust-lang/src/vm/thread.rs
+++ b/dust-lang/src/vm/thread.rs
@@ -1,6 +1,4 @@
-use std::fmt::{self, Display, Formatter};
-
-use tracing::info;
+use tracing::{info, trace};
 
 use crate::{vm::FunctionCall, Chunk, DustString, Value};
 
@@ -16,15 +14,6 @@ impl Thread {
     }
 
     pub fn run(&mut self) -> Option<Value> {
-        let mut call_stack = Stack::with_capacity(self.chunk.prototypes.len() + 1);
-        let mut records = Stack::with_capacity(self.chunk.prototypes.len() + 1);
-        let main_call = FunctionCall {
-            name: self.chunk.name.clone(),
-            return_register: 0,
-            ip: 0,
-        };
-        let main_record = Record::new(&self.chunk);
-
         info!(
             "Starting thread with {}",
             self.chunk
@@ -33,28 +22,47 @@ impl Thread {
                 .unwrap_or_else(|| DustString::from("anonymous"))
         );
 
+        let mut call_stack = Stack::with_capacity(self.chunk.prototypes.len() + 1);
+        let mut records = Stack::with_capacity(self.chunk.prototypes.len() + 1);
+        let main_call = FunctionCall {
+            name: self.chunk.name.clone(),
+            return_register: 0, // Never used, the main function's return is the thread's return
+            ip: 0,
+        };
+        let main_record = Record::new(&self.chunk);
+
         call_stack.push(main_call);
         records.push(main_record);
 
+        let first_action = RunAction::from(*self.chunk.instructions.first().unwrap());
         let mut thread_data = ThreadData {
             call_stack,
             records,
+            next_action: first_action,
+            return_value_index: None,
         };
 
-        let mut next_action = RunAction::from(*self.chunk.instructions.first().unwrap());
-
         loop {
-            let signal = (next_action.logic)(next_action.instruction, &mut thread_data);
+            trace!("Instruction: {}", thread_data.next_action.instruction);
 
-            match signal {
-                ThreadSignal::Continue(action) => {
-                    next_action = action;
-                }
-                ThreadSignal::End(value_option) => {
-                    info!("Thread ended");
+            let should_end = (thread_data.next_action.logic)(
+                thread_data.next_action.instruction,
+                &mut thread_data,
+            );
 
-                    return value_option;
-                }
+            if should_end {
+                let return_value = if let Some(register_index) = thread_data.return_value_index {
+                    let value = thread_data
+                        .records
+                        .last_mut_unchecked()
+                        .empty_register_or_clone_constant_unchecked(register_index);
+
+                    Some(value)
+                } else {
+                    None
+                };
+
+                return return_value;
             }
         }
     }
@@ -64,16 +72,6 @@ impl Thread {
 pub struct ThreadData<'a> {
     pub call_stack: Stack<FunctionCall>,
     pub records: Stack<Record<'a>>,
-}
-
-#[derive(Debug)]
-pub enum ThreadSignal {
-    Continue(RunAction),
-    End(Option<Value>),
-}
-
-impl Display for ThreadSignal {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "{:?}", self)
-    }
+    pub next_action: RunAction,
+    pub return_value_index: Option<u8>,
 }