diff --git a/src/init.cpp b/src/init.cpp
index 16598ada4..7f10a32e4 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -351,6 +351,7 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += HelpMessageOpt("-txindex", strprintf(_("Maintain a full transaction index, used by the getrawtransaction rpc call (default: %u)"), DEFAULT_TXINDEX));
 
     strUsage += HelpMessageOpt("-addressindex", strprintf(_("Maintain a full address index, used to query for the balance, txids and unspent outputs for addresses (default: %u)"), DEFAULT_ADDRESSINDEX));
+    strUsage += HelpMessageOpt("-timestampindex", strprintf(_("Maintain a timestamp index for block hashes, used to query blocks hashes by a range of timestamps (default: %u)"), DEFAULT_TIMESTAMPINDEX));
 
     strUsage += HelpMessageGroup(_("Connection options:"));
     strUsage += HelpMessageOpt("-addnode=<ip>", _("Add a node to connect to and attempt to keep the connection open"));