diff --git a/README.md b/README.md
index 5c109fe..c061f3c 100644
--- a/README.md
+++ b/README.md
@@ -66,7 +66,7 @@ OPENDKIM_USERID="opendkim:opendkim"
 OPENDKIM_SOCKET="inet:8892@0.0.0.0"
 
 # Domain whose mail should be signed.
-OPENDKIM_DOMAIN="*"
+OPENDKIM_DOMAIN="example.com"
 
 # DKIM selector.
 OPENDKIM_SELECTOR="dkim"