diff --git a/dust-lang/src/chunk.rs b/dust-lang/src/chunk.rs
index 461227f..89bdd27 100644
--- a/dust-lang/src/chunk.rs
+++ b/dust-lang/src/chunk.rs
@@ -76,11 +76,18 @@ impl Chunk {
             .ok_or(ChunkError::InstructionUnderflow { position })
     }
 
-    pub fn get_last_instruction(&self) -> Option<&(Instruction, Span)> {
-        self.instructions.last()
+    pub fn get_last_instruction(&self) -> Result<(&Instruction, &Span), ChunkError> {
+        let (instruction, position) =
+            self.instructions
+                .last()
+                .ok_or_else(|| ChunkError::InstructionUnderflow {
+                    position: Span(0, 0),
+                })?;
+
+        Ok((instruction, position))
     }
 
-    pub fn get_last_operation(&self) -> Option<Operation> {
+    pub fn get_last_operation(&self) -> Result<Operation, ChunkError> {
         self.get_last_instruction()
             .map(|(instruction, _)| instruction.operation())
     }
diff --git a/dust-lang/src/identifier.rs b/dust-lang/src/identifier.rs
index f6744eb..55621c5 100644
--- a/dust-lang/src/identifier.rs
+++ b/dust-lang/src/identifier.rs
@@ -1,17 +1,15 @@
 //! Key used to identify a value or type.
 //!
-//! Identifiers are used to uniquely identify values and types in Dust programs. They are
-//! cached to avoid duplication. This means that two identifiers with the same text are the same
-//! object in memory.
+//! Identifiers are used to uniquely identify values and types in Dust programs.
 //!
 //! # Examples
 //! ```
 //! # use dust_lang::Identifier;
 //! let foo = Identifier::new("foo");
-//! let also_foo = Identifier::new("foo");
-//! let another_foo = Identifier::new("foo");
+//! let also_foo = foo.clone();
+//! let another_foo = also_foo.clone();
 //!
-//! assert_eq!(foo.strong_count(), 4); // One for each of the above and one for the cache.
+//! assert_eq!(foo.strong_count(), 3); // One for each of the above.
 //! ```
 use std::{
     fmt::{self, Display, Formatter},
@@ -27,7 +25,6 @@ use serde::{de::Visitor, Deserialize, Serialize};
 pub struct Identifier(Arc<String>);
 
 impl Identifier {
-    /// Creates a new identifier or returns a clone of an existing one from a cache.
     pub fn new<T: ToString>(text: T) -> Self {
         let string = text.to_string();
 
diff --git a/dust-lang/src/instruction.rs b/dust-lang/src/instruction.rs
index 06a9972..a29d2a9 100644
--- a/dust-lang/src/instruction.rs
+++ b/dust-lang/src/instruction.rs
@@ -41,12 +41,12 @@ impl Instruction {
         instruction
     }
 
-    pub fn load_list(to_register: u8, start_register: u8, list_length: u8) -> Instruction {
+    pub fn load_list(to_register: u8, start_register: u8, end_register: u8) -> Instruction {
         let mut instruction = Instruction(Operation::LoadList as u32);
 
         instruction.set_a(to_register);
         instruction.set_b(start_register);
-        instruction.set_c(list_length);
+        instruction.set_c(end_register);
 
         instruction
     }
@@ -371,12 +371,9 @@ impl Instruction {
             Operation::LoadList => {
                 let destination = self.a();
                 let first_index = self.b();
-                let last_index = destination.saturating_sub(1);
+                let last_index = self.c();
 
-                Some(format!(
-                    "R{} = [R{}..=R{}]",
-                    destination, first_index, last_index
-                ))
+                Some(format!("R{destination} = [R{first_index}..=R{last_index}]",))
             }
             Operation::DefineLocal => {
                 let destination = self.a();
diff --git a/dust-lang/src/parser/mod.rs b/dust-lang/src/parser/mod.rs
index 9b695f2..1cb927d 100644
--- a/dust-lang/src/parser/mod.rs
+++ b/dust-lang/src/parser/mod.rs
@@ -40,7 +40,7 @@ impl<'src> Parser<'src> {
     pub fn new(mut lexer: Lexer<'src>) -> Result<Self, ParseError> {
         let (current_token, current_position) = lexer.next_token()?;
 
-        log::trace!("Starting parser with token \"{current_token}\" at {current_position}");
+        log::info!("Starting parser with token \"{current_token}\" at {current_position}");
 
         Ok(Parser {
             lexer,
@@ -96,7 +96,7 @@ impl<'src> Parser<'src> {
 
         let (new_token, position) = self.lexer.next_token()?;
 
-        log::trace!("Parsing \"{new_token}\" at {position}");
+        log::info!("Parsing \"{new_token}\" at {position}");
 
         self.previous_token = replace(&mut self.current_token, new_token);
         self.previous_position = replace(&mut self.current_position, position);
@@ -438,7 +438,7 @@ impl<'src> Parser<'src> {
             ]
         };
 
-        while let Some(operation) = self.chunk.get_last_operation() {
+        while let Ok(operation) = self.chunk.get_last_operation() {
             if operation.is_math() {
                 let (instruction, position) = self.chunk.pop_instruction(self.current_position)?;
 
@@ -688,14 +688,13 @@ impl<'src> Parser<'src> {
         self.advance()?;
 
         let start_register = self.current_register;
-        let mut length = 0;
 
         while !self.allow(TokenKind::RightSquareBrace)? && !self.is_eof() {
             let next_register = self.current_register;
 
             self.parse(Precedence::Assignment)?; // Do not allow assignment
 
-            if let Some(Operation::LoadConstant) = self.chunk.get_last_operation() {
+            if let Operation::LoadConstant = self.chunk.get_last_operation()? {
                 self.increment_register()?;
             }
 
@@ -706,19 +705,16 @@ impl<'src> Parser<'src> {
                 );
             }
 
-            length += 1;
-
             if !self.allow(TokenKind::Comma)? {
                 self.expect(TokenKind::RightSquareBrace)?;
-
-                break;
             }
         }
 
+        let end_register = self.current_register - 1;
         let end = self.current_position.1;
 
         self.emit_instruction(
-            Instruction::load_list(self.current_register, start_register, length),
+            Instruction::load_list(self.current_register, start_register, end_register),
             Span(start, end),
         );
         self.increment_register()?;
@@ -864,17 +860,11 @@ impl<'src> Parser<'src> {
         self.parse_expression()?;
         self.increment_register()?;
 
-        let (previous_instruction, previous_position) = *self
-            .chunk
-            .get_last_instruction()
-            .ok_or_else(|| ParseError::ExpectedExpression {
-                found: self.current_token.to_owned(),
-                position,
-            })?;
+        let (previous_instruction, previous_position) = self.chunk.get_last_instruction()?;
         let register = previous_instruction.a();
         let local_index =
             self.chunk
-                .declare_local(identifier, is_mutable, register, previous_position)?;
+                .declare_local(identifier, is_mutable, register, *previous_position)?;
 
         // Optimize for assignment to a comparison
         // if let Operation::Jump = previous_instruction.operation() {
@@ -909,8 +899,8 @@ impl<'src> Parser<'src> {
         let allow_return = precedence == Precedence::None;
 
         if let Some(prefix_parser) = ParseRule::from(&self.current_token.kind()).prefix {
-            log::trace!(
-                "Parsing \"{}\" as prefix at precedence {precedence}",
+            log::debug!(
+                "Prefix \"{}\" has precedence {precedence}",
                 self.current_token,
             );
 
@@ -921,8 +911,8 @@ impl<'src> Parser<'src> {
 
         while precedence <= infix_rule.precedence {
             if let Some(infix_parser) = infix_rule.infix {
-                log::trace!(
-                    "Parsing \"{}\" as infix at precedence {precedence}",
+                log::debug!(
+                    "Infix \"{}\" has precedence {precedence}",
                     self.current_token,
                 );
 
diff --git a/dust-lang/src/parser/tests.rs b/dust-lang/src/parser/tests.rs
index 8b8d62d..2370385 100644
--- a/dust-lang/src/parser/tests.rs
+++ b/dust-lang/src/parser/tests.rs
@@ -321,7 +321,7 @@ fn list_with_complex_expression() {
                 ),
                 (Instruction::subtract(3, 1, 2), Span(10, 11)),
                 (Instruction::close(1, 3), Span(17, 18)),
-                (Instruction::load_list(4, 0, 2), Span(0, 18)),
+                (Instruction::load_list(4, 0, 3), Span(0, 18)),
                 (Instruction::end(true), Span(18, 18)),
             ],
             vec![
@@ -352,7 +352,7 @@ fn list_with_simple_expression() {
                     Span(6, 7)
                 ),
                 (Instruction::load_constant(2, 3), Span(11, 12)),
-                (Instruction::load_list(3, 0, 3), Span(0, 13)),
+                (Instruction::load_list(3, 0, 2), Span(0, 13)),
                 (Instruction::end(true), Span(13, 13)),
             ],
             vec![
@@ -377,7 +377,7 @@ fn list() {
                 (Instruction::load_constant(0, 0), Span(1, 2)),
                 (Instruction::load_constant(1, 1), Span(4, 5)),
                 (Instruction::load_constant(2, 2), Span(7, 8)),
-                (Instruction::load_list(3, 0, 3), Span(0, 9)),
+                (Instruction::load_list(3, 0, 2), Span(0, 9)),
                 (Instruction::end(true), Span(9, 9)),
             ],
             vec![Value::integer(1), Value::integer(2), Value::integer(3),],
diff --git a/dust-lang/src/vm.rs b/dust-lang/src/vm.rs
index f82be12..0101f9f 100644
--- a/dust-lang/src/vm.rs
+++ b/dust-lang/src/vm.rs
@@ -56,7 +56,7 @@ impl Vm {
         }
 
         while let Ok((instruction, position)) = self.read(Span(0, 0)).copied() {
-            log::trace!(
+            log::info!(
                 "Running IP {} {} at {position}",
                 self.ip - 1,
                 instruction.operation()
@@ -68,6 +68,8 @@ impl Vm {
                     let to = instruction.a();
                     let value = self.take(from, position)?;
 
+                    log::debug!("R{from} -{{{value}}}-> R{to}");
+
                     self.insert(value, to, position)?;
                 }
                 Operation::Close => {
@@ -100,13 +102,14 @@ impl Vm {
                 Operation::LoadList => {
                     let to_register = instruction.a();
                     let first_register = instruction.b();
-                    let length = instruction.c();
-                    let last_register = first_register + length + 1;
-
+                    let last_register = instruction.c();
+                    let length = last_register - first_register + 1;
                     let mut list = Vec::with_capacity(length as usize);
 
+                    log::debug!("R{to_register} = [R{first_register}..=R{last_register}]");
+
                     for register_index in first_register..=last_register {
-                        let value = match self.clone(register_index, position) {
+                        let value = match self.take(register_index, position) {
                             Ok(value) => value,
                             Err(VmError::EmptyRegister { .. }) => continue,
                             Err(error) => return Err(error),
@@ -126,81 +129,91 @@ impl Vm {
                 Operation::GetLocal => {
                     let register_index = instruction.a();
                     let local_index = instruction.b();
-                    let local = self.chunk.get_local(local_index, position)?.clone();
-                    let value = self.clone_as_variable(local, position)?;
+                    let local = self.chunk.get_local(local_index, position)?;
+                    let value = if let Some(index) = local.register_index {
+                        self.take(index, position)?
+                    } else {
+                        return Err(VmError::UndefinedVariable {
+                            identifier: local.identifier.clone(),
+                            position,
+                        });
+                    };
 
                     self.insert(value, register_index, position)?;
                 }
                 Operation::SetLocal => {
                     let register_index = instruction.a();
                     let local_index = instruction.b();
-                    let local = self.chunk.get_local(local_index, position)?.clone();
-                    let value = self.clone_as_variable(local, position)?;
+                    let local = self.chunk.get_local(local_index, position)?;
+                    let value = if let Some(index) = local.register_index {
+                        self.take(index, position)?
+                    } else {
+                        return Err(VmError::UndefinedVariable {
+                            identifier: local.identifier.clone(),
+                            position,
+                        });
+                    };
+
                     let new_value = if instruction.b_is_constant() {
                         self.chunk.take_constant(register_index, position)?
                     } else {
-                        self.clone(register_index, position)?
+                        self.take(register_index, position)?
                     };
 
                     value
                         .mutate(new_value)
                         .map_err(|error| VmError::Value { error, position })?;
-
                     self.insert(value, register_index, position)?;
                 }
                 Operation::Add => {
                     let (left, right) = get_arguments(self, instruction, position)?;
-
-                    log::debug!("{left} + {right}");
-
                     let sum = left
                         .add(right)
                         .map_err(|error| VmError::Value { error, position })?;
 
+                    log::debug!("{left} + {right} = {sum}");
+
                     self.insert(sum, instruction.a(), position)?;
                 }
                 Operation::Subtract => {
                     let (left, right) = get_arguments(self, instruction, position)?;
-
-                    log::debug!("{left} - {right}");
-
                     let difference = left
                         .subtract(right)
                         .map_err(|error| VmError::Value { error, position })?;
 
+                    log::debug!("{left} - {right} = {difference}");
+
                     self.insert(difference, instruction.a(), position)?;
                 }
                 Operation::Multiply => {
                     let (left, right) = get_arguments(self, instruction, position)?;
 
-                    log::debug!("{left} * {right}");
-
                     let product = left
                         .multiply(right)
                         .map_err(|error| VmError::Value { error, position })?;
 
+                    log::debug!("{position} {left} * {right}");
+
                     self.insert(product, instruction.a(), position)?;
                 }
                 Operation::Divide => {
                     let (left, right) = get_arguments(self, instruction, position)?;
-
-                    log::debug!("{left} / {right}");
-
                     let quotient = left
                         .divide(right)
                         .map_err(|error| VmError::Value { error, position })?;
 
+                    log::debug!("{left} / {right} = {quotient}");
+
                     self.insert(quotient, instruction.a(), position)?;
                 }
                 Operation::Modulo => {
                     let (left, right) = get_arguments(self, instruction, position)?;
-
-                    log::debug!("{left} % {right}");
-
                     let remainder = left
                         .modulo(right)
                         .map_err(|error| VmError::Value { error, position })?;
 
+                    log::debug!("{left} % {right} = {remainder}");
+
                     self.insert(remainder, instruction.a(), position)?;
                 }
                 Operation::Test => {
@@ -238,6 +251,7 @@ impl Vm {
                     debug_assert_eq!(jump.operation(), Operation::Jump);
 
                     let (left, right) = get_arguments(self, instruction, position)?;
+
                     let boolean = left
                         .equal(right)
                         .map_err(|error| VmError::Value { error, position })?
@@ -248,6 +262,8 @@ impl Vm {
                         })?;
                     let compare_to = instruction.a_as_boolean();
 
+                    log::debug!("{left} == {right} = {boolean} == {compare_to}");
+
                     if boolean == compare_to {
                         self.ip += 1;
                     } else {
@@ -263,11 +279,12 @@ impl Vm {
                     }
                 }
                 Operation::Less => {
-                    let (jump, _) = *self.chunk.get_instruction(self.ip, position)?;
+                    let jump = self.chunk.get_instruction(self.ip, position)?.0;
 
                     debug_assert_eq!(jump.operation(), Operation::Jump);
 
                     let (left, right) = get_arguments(self, instruction, position)?;
+
                     let boolean = left
                         .less_than(right)
                         .map_err(|error| VmError::Value { error, position })?
@@ -278,6 +295,8 @@ impl Vm {
                         })?;
                     let compare_to = instruction.a_as_boolean();
 
+                    log::debug!("{left} < {right} = {boolean} == {compare_to}");
+
                     if boolean == compare_to {
                         self.ip += 1;
                     } else {
@@ -293,7 +312,7 @@ impl Vm {
                     }
                 }
                 Operation::LessEqual => {
-                    let (jump, _) = *self.chunk.get_instruction(self.ip, position)?;
+                    let jump = self.chunk.get_instruction(self.ip, position)?.0;
 
                     debug_assert_eq!(jump.operation(), Operation::Jump);
 
@@ -308,6 +327,8 @@ impl Vm {
                         })?;
                     let compare_to = instruction.a_as_boolean();
 
+                    log::debug!("{left} <= {right} = {boolean} == {compare_to}");
+
                     if boolean == compare_to {
                         self.ip += 1;
                     } else {
@@ -332,6 +353,8 @@ impl Vm {
                         .negate()
                         .map_err(|error| VmError::Value { error, position })?;
 
+                    log::debug!("-({value}) = {negated}");
+
                     self.insert(negated, instruction.a(), position)?;
                 }
                 Operation::Not => {
@@ -344,6 +367,8 @@ impl Vm {
                         .not()
                         .map_err(|error| VmError::Value { error, position })?;
 
+                    log::debug!("!{value} = {not}");
+
                     self.insert(not, instruction.a(), position)?;
                 }
                 Operation::Jump => {
diff --git a/dust-shell/src/main.rs b/dust-shell/src/main.rs
index 5ea02cc..1618fba 100644
--- a/dust-shell/src/main.rs
+++ b/dust-shell/src/main.rs
@@ -24,21 +24,21 @@ fn main() {
         .parse_env("DUST_LOG")
         .format(|buf, record| {
             let level = match record.level() {
-                Level::Error => "ERROR".red(),
-                Level::Warn => "WARN".yellow(),
-                Level::Info => "INFO".white(),
-                Level::Debug => "DEBUG".blue(),
-                Level::Trace => "TRACE".purple(),
+                Level::Info => "INFO".white().bold(),
+                Level::Debug => "DEBUG".blue().bold(),
+                Level::Warn => "WARN".yellow().bold(),
+                Level::Error => "ERROR".red().bold(),
+                Level::Trace => "TRACE".purple().bold(),
             }
             .bold();
-            let level_display = format!("[{level:^5}]").white().on_black();
+            let level_display = format!("{level:<5}");
             let module = record
                 .module_path()
-                .map(|path| path.split("::").last().unwrap_or("unknown"))
+                .map(|path| path.split("::").last().unwrap_or(path))
                 .unwrap_or("unknown")
                 .dimmed();
 
-            writeln!(buf, "{level_display} {module:^6} {}", record.args())
+            writeln!(buf, "{level_display:^10} {module:^6} {}", record.args())
         })
         .init();