diff --git a/super-tiny-compiler.js b/super-tiny-compiler.js
index e4e214d..ea9c051 100644
--- a/super-tiny-compiler.js
+++ b/super-tiny-compiler.js
@@ -446,7 +446,7 @@ function tokenizer(input) {
     //    ^^^
     //    Name token
     //
-    var LETTERS = /[a-z]/i;
+    var LETTERS = /[a-zA-Z_0-9]/;
     if (LETTERS.test(char)) {
       var value = '';
 
@@ -934,4 +934,4 @@ module.exports = {
   transformer: transformer,
   codeGenerator: codeGenerator,
   compiler: compiler
-};
+};
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