diff --git a/README.md b/README.md
index e992533..25493c1 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,10 @@ A library providing an ACN (Anonymous Communication Network
 
 * Tor v3 Onion Services
 
+## Environment Variables
+
+- `TOR_LD_LIBRARY_PATH` - override the library path given to the Tor process as different from the one given to the parent process.
+
 ## Requirements for ACN Support
 
 * Reference an EndPoint via a string / hostname