diff --git a/hs20/server/ca/ocsp-update-cache.sh b/hs20/server/ca/ocsp-update-cache.sh
index 8ddef9b9c..f2b23250c 100755
--- a/hs20/server/ca/ocsp-update-cache.sh
+++ b/hs20/server/ca/ocsp-update-cache.sh
@@ -1,5 +1,6 @@
 #!/bin/sh
 
+# NOTE: You may need to replace 'localhost' with your OCSP server hostname.
 openssl ocsp \
 	-no_nonce \
 	-CAfile ca.pem \