diff --git a/src/fs/mod.zig b/src/fs/mod.zig
index 6f03d3f032..531973b3af 100644
--- a/src/fs/mod.zig
+++ b/src/fs/mod.zig
@@ -1 +1,6 @@
+//! Filesystem abstraction for the Roc compiler.
+//!
+//! This module provides a filesystem interface that allows for easy testing
+//! and mocking of file operations throughout the compiler.
+
 pub const Filesystem = @import("Filesystem.zig");