diff --git a/src/bin/topola/cli.rs b/src/bin/topola/cli.rs
index c4053ea..1455631 100644
--- a/src/bin/topola/cli.rs
+++ b/src/bin/topola/cli.rs
@@ -8,8 +8,8 @@ pub struct Cli {
     #[arg(value_name = "SPECCTRA DESIGN FILE",
 	  help = "Specify the Specctra Design (*.dsn) input file for the Topola autorouter")]
     pub input: PathBuf,
-    #[arg(short, long, value_name = "SESSION FILE",
-	  help = "Specify the output Topola session file (*.ses), by default, it is the input filename with extension changed to .ses")
+    #[arg(short, long, value_name = "SPECCTRA SESSION FILE",
+	  help = "Specify the output session file in Specctra-compatible format (*.ses). The input filename is used by default, with the extension changed to Specctra Session File extension")
     ]
     pub output: Option<PathBuf>,
     #[arg(short, long, value_name = "COMMAND FILE", help = "JSON-like file with .cmd extension, containing sequence of available commands ")]