diff --git a/CLAUDE.md b/CLAUDE.md
index 658a642..86e8ab9 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -111,6 +111,19 @@ IPX/TCP → nwtransport → nwconn (dispatcher) → NCP providers
 - **TUI:** do not add new direct `curses.h` users; route future interactive tools through `nwtui`/`nwi18n` and the `nwtoolbox` applet model.
 - **Transport:** TCP/IP is a future split under `nwtransport`, not a new daemon. NCP providers stay transport-neutral.
 
+### Original NSS reference sources
+
+The original NSS sources are available on the host at `/home/mario/mars/nss`:
+
+```
+/home/mario/mars/nss/public_core/   — comn, nss, library, lsa, manage, ndpmod, nebdrv, sharedsrc, …
+/home/mario/mars/nss/shared/sdk/    — include, internal, public, comnSA headers
+```
+
+Use these directly for comparison when importing or auditing files into
+`src/nwnss/` and `include/nwnss/`.  The provenance mapping is in the section
+below.
+
 ### NSS import layout
 
 Imported NSS sources follow provenance-preserving paths: