diff --git a/assembler/src/assembler/engine.rs b/assembler/src/assembler/engine.rs
index 72628a7..cfc19b2 100644
--- a/assembler/src/assembler/engine.rs
+++ b/assembler/src/assembler/engine.rs
@@ -60,11 +60,7 @@ impl CompilerEngine {
     }
 
     /// Main assembly function that orchestrates the entire compilation process.
-    pub fn assemble(
-        &self,
-        main_path: &Path,
-        output_path: Option<&Path>,
-    ) -> Result<Vec<Instruction>, AssembleError> {
+    pub fn assemble(&self, main_path: &Path) -> Result<Vec<Instruction>, AssembleError> {
         let program = Program::new();
 
         // Set the main path in the program
@@ -139,23 +135,19 @@ impl Default for CompilerEngine {
 /// Convenience function for simple assembly with default settings.
 pub fn assemble(input_path: &Path) -> Result<Vec<Instruction>, AssembleError> {
     let engine = CompilerEngine::new();
-    engine.assemble(input_path, None)
+    engine.assemble(input_path)
 }
 
 /// Convenience function for assembling to ELF object format.
-pub fn assemble_to_object(
-    input_path: &Path,
-    output_path: Option<&Path>,
-) -> Result<Vec<Instruction>, AssembleError> {
+pub fn assemble_to_object(input_path: &Path) -> Result<Vec<Instruction>, AssembleError> {
     let engine = CompilerEngine::with_output_format(OutputFormat::ElfObject);
-    engine.assemble(input_path, output_path)
+    engine.assemble(input_path)
 }
 
 /// Convenience function for assembling to ELF executable format.
 pub fn assemble_to_executable(
     input_path: &Path,
-    output_path: Option<&Path>,
 ) -> Result<Vec<Instruction>, AssembleError> {
     let engine = CompilerEngine::with_output_format(OutputFormat::ElfExecutable);
-    engine.assemble(input_path, output_path)
+    engine.assemble(input_path)
 }
diff --git a/assembler/src/assembler/lexer.rs b/assembler/src/assembler/lexer.rs
index f5adfb5..9b624a4 100644
--- a/assembler/src/assembler/lexer.rs
+++ b/assembler/src/assembler/lexer.rs
@@ -56,7 +56,7 @@ pub fn lexer(mut program: String, module: u64) -> Result<Vec<Token>, AssembleErr
             } else if let Some(token) = parse_symbol(token, module)? {
                 tokens.push(token);
             } else {
-                return Err(AssembleError::Generic);
+                return Err(AssembleError::Generic("Token not matched!".to_string()));
             }
         }
     }
diff --git a/assembler/src/assembler/model.rs b/assembler/src/assembler/model.rs
index 615b7da..5173f49 100644
--- a/assembler/src/assembler/model.rs
+++ b/assembler/src/assembler/model.rs
@@ -157,7 +157,7 @@ impl PartialEq for Symbol {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub enum Token {
+pub enum TokenType {
     Symbol(Symbol),
     Register(Register),
     Immediate(u32),
@@ -165,26 +165,19 @@ pub enum Token {
     Opcode(Opcode),
 }
 
-#[derive(Debug, PartialEq, Eq, Copy, Clone)]
-pub enum TokenType {
-    Symbol,
-    Register,
-    Immediate,
-    StringLit,
-    Opcode,
+pub struct Token {
+    token_type: TokenType,
+    source_info: SourceInfo,
 }
 
-impl TokenType {
-    #[must_use]
-    pub const fn from_token(token: &Token) -> Self {
-        match token {
-            Token::Symbol(_) => Self::Symbol,
-            Token::Register(_) => Self::Register,
-            Token::Immediate(_) => Self::Immediate,
-            Token::StringLit(_) => Self::StringLit,
-            Token::Opcode(_) => Self::Opcode,
-        }
-    }
+///  Information on where the token is within the source.
+pub struct SourceInfo {
+    /// The line number within the source file underpinned by `module_id`.
+    pub line_no: usize,
+    /// The ID of the module containing this token.
+    pub module_id: Uuid,
+    /// The indexes where this token may be found (line-local).
+    pub span: std::ops::Range<usize>,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]