diff --git a/src/syntax/mod.rs b/src/syntax/mod.rs
index 483656f..20892d3 100644
--- a/src/syntax/mod.rs
+++ b/src/syntax/mod.rs
@@ -1,3 +1,6 @@
+//! Syntax related modules for lowering
+//! source code into AST
+
 pub mod ast;
 pub mod lexer;
 pub mod parser;