diff --git a/doc/upgrade.md b/doc/upgrade.md
index 2bd7f0f..df5c289 100644
--- a/doc/upgrade.md
+++ b/doc/upgrade.md
@@ -44,4 +44,4 @@ If updating from versions below 0.21, you may need to add `wallet=wallet.dat` to
 
 #### Update core versions
 
-    basicswap-prepare -preparebinonly --withcoins=monero,bitcoin
+    basicswap-prepare --datadir=$SWAP_DATADIR -preparebinonly --withcoins=monero,bitcoin