diff --git a/src/cminus.l b/src/cminus.l
index 486c61d..59a5123 100644
--- a/src/cminus.l
+++ b/src/cminus.l
@@ -16,7 +16,7 @@ char tokenString[MAXTOKENLEN+1];
 digit       [0-9]
 number      {digit}+
 letter      [a-zA-Z]
-identifier  {letter}+
+identifier  {letter}({letter}|{digit})*
 newline     \n
 whitespace  [ \t]+