diff --git a/assembler/src/source/token.rs b/assembler/src/source/token.rs
index f327295..2303961 100644
--- a/assembler/src/source/token.rs
+++ b/assembler/src/source/token.rs
@@ -2,6 +2,8 @@
 //! easier to build from scratch and edit his code than it would be to try and wrangle it
 //! into shape.
 
+use common::prelude::*;
+
 use crate::source::{
     source_info::SourceInfo,
     token_info::{
@@ -71,8 +73,8 @@ impl Token {
     }
 
     #[must_use]
-    pub const fn register(name: String, source_info: SourceInfo) -> Self {
-        Self::new(TokenType::Register(RegisterToken { name }), source_info)
+    pub const fn register(reg: Register, source_info: SourceInfo) -> Self {
+        Self::new(TokenType::Register(RegisterToken { reg }), source_info)
     }
 
     #[must_use]
diff --git a/assembler/src/source/token_info.rs b/assembler/src/source/token_info.rs
index af5fdcd..2f916fe 100644
--- a/assembler/src/source/token_info.rs
+++ b/assembler/src/source/token_info.rs
@@ -1,3 +1,5 @@
+use common::prelude::Register;
+
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct SymbolToken {
     pub name: String,
@@ -15,7 +17,14 @@ pub struct DirectiveToken {
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct RegisterToken {
-    pub name: String,
+    pub reg: Register,
+}
+
+impl RegisterToken {
+    /// Returns the name of a valid [`Register`]
+    pub fn name(&self) -> String {
+        self.reg.to_string()
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
diff --git a/assembler/src/source/tokeniser.rs b/assembler/src/source/tokeniser.rs
index 6834c73..c4620a6 100644
--- a/assembler/src/source/tokeniser.rs
+++ b/assembler/src/source/tokeniser.rs
@@ -8,6 +8,8 @@ use std::{
 
 use regex::Regex;
 
+use common::prelude::*;
+
 use crate::{
     context::AssemblerContext,
     error::{AssembleError, AssembleErrorKind, IoError, IoErrorKind},
@@ -36,10 +38,10 @@ pub struct Tokeniser {
 
     // Pre-compiled regex patterns
     label_regex: Regex,
-    register_regex: Regex,
+    // register_regex: Regex,
     immediate_regex: Regex,
     directive_regex: Regex,
-    instruction_regex: Regex,
+    // instruction_regex: Regex,
     symbol_regex: Regex,
     string_regex: Regex,
     comment_regex: Regex,
@@ -54,18 +56,18 @@ impl Tokeniser {
 
             label_regex: Regex::new(r"^([a-zA-Z_][a-zA-Z0-9_]*):")
                 .expect("Failed to compile label regex pattern"),
-            register_regex: Regex::new(r"^(r[0-9]+|sp|fp|pc)")
-                .expect("Failed to compile register regex pattern"),
+            // register_regex: Regex::new(r"^(r[0-9]+|sp|fp|pc)")
+            //     .expect("Failed to compile register regex pattern"),
             immediate_regex: Regex::new(
                 r"^(0x[0-9a-fA-F_]+|0b[0-1_]+|0o[0-7_]+|[0-9_]+)",
             )
             .expect("Failed to compile immediate regex pattern"),
             directive_regex: Regex::new(r"^\.([a-zA-Z]+)")
                 .expect("Failed to compile directive regex pattern"),
-            instruction_regex: Regex::new(
-                r"^(add|sub|mul|div|jmp|call|ret|lli|nop|halt)",
-            )
-            .expect("Failed to compile instruction regex pattern"),
+            // instruction_regex: Regex::new(
+            //     r"^(add|sub|mul|div|jmp|call|ret|lli|nop|halt)",
+            // )
+            // .expect("Failed to compile instruction regex pattern"),
             symbol_regex: Regex::new(r"^([a-zA-Z_][a-zA-Z0-9_]*)")
                 .expect("Failed to compile symbol regex pattern"),
             string_regex: Regex::new(r#"^"([^"]*)"#)
@@ -186,11 +188,19 @@ impl Tokeniser {
     }
 
     fn try_match_register(&self, input: &str) -> Option<(TokenType, usize)> {
-        let caps = self.register_regex.captures(input)?;
-        let name = caps.get(1)?.as_str().to_string();
-        let len = caps.get(0)?.len();
+        _ = self;
 
-        Some((TokenType::Register(RegisterToken { name }), len))
+        let reg = match Register::try_from(input) {
+            Ok(reg) => reg,
+            Err(_why) => {
+                // Probably ignore the error.
+                return None;
+            }
+        };
+
+        let len = input.len();
+
+        Some((TokenType::Register(RegisterToken { reg }), len))
     }
 
     fn try_match_immediate(&self, input: &str) -> Option<(TokenType, usize)> {
@@ -224,12 +234,15 @@ impl Tokeniser {
         Some((TokenType::Directive(DirectiveToken { directive }), len))
     }
 
-    fn try_match_instruction(&self, input: &str) -> Option<(TokenType, usize)> {
-        let caps = self.instruction_regex.captures(input)?;
-        let mnemonic = caps.get(1)?.as_str().to_string();
-        let len = caps.get(0)?.len();
+    const fn try_match_instruction(&self, _input: &str) -> Option<(TokenType, usize)> {
+        _ = self;
 
-        Some((TokenType::Instruction(InstructionToken { mnemonic }), len))
+        // let instruction =
+        // Some((TokenType::Instruction(InstructionToken { mnemonic }), len))
+
+        // TODO: fix me.
+
+        None
     }
 
     fn try_match_symbol(&self, input: &str) -> Option<(TokenType, usize)> {
diff --git a/assembler/src/source/tokeniser/tests.rs b/assembler/src/source/tokeniser/tests.rs
index f36f003..da73fba 100644
--- a/assembler/src/source/tokeniser/tests.rs
+++ b/assembler/src/source/tokeniser/tests.rs
@@ -90,19 +90,13 @@ fn test_all_instructions() {
 
 #[test]
 fn test_registers() {
-    let test_cases = [
-        ("r0", "r0"),
-        ("r15", "r15"),
-        ("sp", "sp"),
-        ("fp", "fp"),
-        ("pc", "pc"),
-    ];
+    let test_cases = [("rg0", "r0"), ("rgf", "rgf"), ("pcx", "pcx")];
 
     for (input, expected) in &test_cases {
         let tokens = tokenize_source(input).expect("Failed to tokenize register");
 
         if let TokenType::Register(reg) = &tokens[0].token_type {
-            assert_eq!(reg.name, *expected);
+            assert_eq!(reg.reg.to_string(), *expected);
         } else {
             panic!("Expected register token for {input}");
         }