diff --git a/src/mango/token/tokens/literal.rs b/src/mango/token/tokens/literal.rs
index 2065dcda..4836de63 100644
--- a/src/mango/token/tokens/literal.rs
+++ b/src/mango/token/tokens/literal.rs
@@ -26,8 +26,21 @@ impl LiteralToken {
         LiteralToken::Real(f64eq::new(value))
     }
 
+    /// This matches integer literals, either just numbers in base 10, or base 2-36 with prefix.
+    /// The syntax for -37 in base 16 is -16b25 and 2748 is 16bABC.
+    /// Incorrect values like 4b7 or 0b0 are not handled at the lexing stage.
     pub fn subpattern_int() -> &'static str {
-        "[a-z]?\""
+        r"(?:\+|-*)(?:[1-9][0-9]*b(?:_?[0-9a-zA-Z])+|[0-9](?:_?[0-9])*)"
+    }
+
+    /// This matches real literals (base 10), which look like this:
+    ///   sign / int1 / period / int2 / e / sign / int
+    /// Here int is a series of 0-9 digits separated by at most one underscore.
+    /// Signs are optional, everything from 'e' is optional, and int1 OR int2 is optional.
+    pub fn subpattern_real() -> &'static str {
+        // TODO: do I want to allow numbers to start with a period?
+        // TODO: for now, only base10 for reals (would 8b11e2 be 9*8^2 or 9*10^2?)
+        r"(?:\+|-*)(?:\d(?:_?\d)*\.\d(?:_?\d)*|\d(?:_?\d)*\.|\.\d(?:_?\d)*)(?:e(?:\+|-|)\d(?:_?\d)*)?"
     }
 }