diff --git a/doc/HACKING.md b/doc/HACKING.md
index 82f681337..07dbeb4e4 100644
--- a/doc/HACKING.md
+++ b/doc/HACKING.md
@@ -314,10 +314,13 @@ Protocol Modifications
 
 The source tree contains CSV files extracted from the v1.0 BOLT
 specifications (wire/extracted_peer_wire_csv and
-wire/extracted_onion_wire_csv).  You can regenerate these by setting
-`BOLTDIR` and `BOLTVERSION` appropriately, and running `make
-extract-bolt-csv`.
+wire/extracted_onion_wire_csv).  You can regenerate these by
+first deleting the local copy(if any) at directory .tmp.lightning-rfc,
+setting `BOLTDIR` and `BOLTVERSION` appropriately, and finally running `make
+extract-bolt-csv`. By default the bolts will be retrieved from the
+directory `../lightning-rfc` and a recent git version.
 
+e.g., `make extract-bolt-csv BOLTDIR=../bolts BOLTVERSION=ee76043271f79f45b3392e629fd35e47f1268dc8`
 
 Further Information
 -------------------