diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index 1c8c1e0d62150..a2742290ecbe5 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -778,7 +778,8 @@ var (
 
 	HTTPRpcTimeoutFlag = cli.StringFlag{
 		Name:  "http.timeout",
-		Usage: "Sets http rpc request timeout",
+		Usage: "Sets http rpc request timeout (use \"s\" suffix for seconds, eg: --http.timeout 10s)",
+		// uses time.ParseDuration() which requires a unit suffix, "h", "m", "s", "ms" etc.
 		Value: fmt.Sprint(ethconfig.Defaults.HTTPRpcTimeout.Nanoseconds(), "ns"),
 	}
 )