diff --git a/SLS_C/include/sls/lexer.h b/SLS_C/include/sls/lexer.h
index b52eed7..18d34af 100644
--- a/SLS_C/include/sls/lexer.h
+++ b/SLS_C/include/sls/lexer.h
@@ -53,7 +53,8 @@ typedef struct {
 } ArrayLiteral;
 
 typedef struct {
-    // TODO
+    const Token *tokens;
+    size_t length;
 } TokenString;
 
 typedef struct {
@@ -75,4 +76,9 @@ typedef struct {
     };
 } Token;
 
+typedef struct TokenStream {
+    Token token;
+    struct TokenStream *next;
+} TokenStream;
+
 #endif // SLS_LEXER_H