diff --git a/hx.hs b/hx.hs
index ce4dc2b..2dbde27 100644
--- a/hx.hs
+++ b/hx.hs
@@ -669,9 +669,9 @@ mainArgs _ = error $ unlines ["Unexpected arguments."
                              ,""
                              ,"# MNEMONICS AND SEED FORMATS"
                              ,"hx mnemonic"
-                             ,"hx bip39-mnemonic                         [0]"
-                             ,"hx bip39-hex                              [0]"
-                             ,"hx bip39-seed <PASSPHRASE>                [0]"
+                             ,"hx bip39-seed [<PASSPHRASE>]           [0][5]"
+                             ,"hx bip39-mnemonic                      [0][5]"
+                             ,"hx bip39-hex                           [0][5]"
                              ,"hx rfc1751-key                            [0]"
                              ,"hx rfc1751-mnemonic                       [0]"
                              ,""
@@ -730,6 +730,9 @@ mainArgs _ = error $ unlines ["Unexpected arguments."
                              ,"     This is for this reason that `hash160` has been added"
                              ,"     (`hx ripemd-hash` is equivalent to `hx encode-hex | hx hash160`"
                              ,"     and `hx hash160` is equivalent to `hx decode-hex | hx ripemd-hash`)."
+                             ,"[5]: The commands `hx bip39-mnemonic` and `hx bip39-hex` are inverse of each other."
+                             ,"     However, this is the command `hx bip39-seed` which must be used to get"
+                             ,"     the root extended private key."
                              ,""
                              ,"PATH      ::= <PATH-HEAD> <PATH-CONT>"
                              ,"PATH-HEAD ::= 'A'   [address (compressed)]"