diff --git a/_roku.sh b/_roku.sh
index 68fe8bc..52e4e23 100755
--- a/_roku.sh
+++ b/_roku.sh
@@ -106,6 +106,7 @@ _roku_san_update()
 _roku_audcap()
 {
     [ -z "$ROKU_DEV_TARGET" ] && echo "ROKU_DEV_TARGET must be defined" && return 0
+    [ -z "$1" ] && echo "Syntax: roku audcap <filename>" && return 0
     __set_master_ip
     __app_cmd "audcap record start 00"
     echo -n "Press Enter to stop capture."