diff --git a/src/common.h b/src/common.h
index c96a9e4..b5284bb 100644
--- a/src/common.h
+++ b/src/common.h
@@ -112,7 +112,7 @@ typedef enum _C99Code
 	C99_CODE_SQUOTE			= CPP_CODE_SQUOTE,
 	C99_CODE_WHITESPACE		= CPP_CODE_WHITESPACE,
 	C99_CODE_WORD			= CPP_CODE_WORD,
-	C99_CODE_CONSTANT,
+	C99_CODE_CONSTANT		= CPP_CODE_LAST + 1,
 	C99_CODE_IDENTIFIER,
 	C99_CODE_KEYWORD_AUTO,
 	C99_CODE_KEYWORD_BREAK,