diff --git a/src/parser.zig b/src/parser.zig
index 746e24a..0bf4055 100644
--- a/src/parser.zig
+++ b/src/parser.zig
@@ -15,16 +15,25 @@ const Node = ast.Node;
 const Expr = ast.Expr;
 const Stmt = ast.Stmt;
 
+const TokenList = std.ArrayList(Token);
+
 pub const Parser = struct {
     allocator: *Allocator,
     scanner: *Scanner,
-
-    tokens: []Token = undefined,
+    tokens: TokenList,
 
     hadError: bool = false,
 
     pub fn init(allocator: *Allocator, scanner: *Scanner) Parser {
-        return Parser{ .allocator = allocator, .scanner = scanner };
+        return Parser{
+            .allocator = allocator,
+            .scanner = scanner,
+            .tokens = TokenList.init(allocator),
+        };
+    }
+
+    pub fn deinit(self: *@This()) void {
+        self.tokens.deinit();
     }
 
     fn doError(self: *Parser, comptime fmt: []const u8, args: ...) void {
@@ -36,11 +45,11 @@ pub const Parser = struct {
     }
 
     fn peek(self: *Parser) Token {
-        return self.tokens[self.tokens.len - 1];
+        return self.tokens.at(self.tokens.len - 1);
     }
 
     fn previous(self: *Parser) Token {
-        return self.tokens[self.tokens.len - 2];
+        return self.tokens.at(self.tokens.len - 2);
     }
 
     fn tokenError(self: *Parser, token: Token, msg: []const u8) Result!void {
@@ -73,12 +82,7 @@ pub const Parser = struct {
             }
         }
 
-        self.tokens = try self.allocator.realloc(
-            self.tokens,
-            self.tokens.len + 1,
-        );
-
-        self.tokens[self.tokens.len - 1] = token;
+        try self.tokens.append(token);
         std.debug.warn("skip to {}\n", token);
         return token;
     }
@@ -306,7 +310,6 @@ pub const Parser = struct {
     }
 
     pub fn parse(self: *Parser) !*ast.Node {
-        self.tokens = try self.allocator.alloc(Token, 0);
         var root = try ast.mkRoot(self.allocator);
 
         var token_opt: ?Token = null;