diff --git a/src/clock.rs b/src/clock.rs
index 162eb0f..c074e8c 100644
--- a/src/clock.rs
+++ b/src/clock.rs
@@ -78,7 +78,7 @@ pub struct Clock {
     #[clap(short = 'u', long, value_parser = humantime::parse_duration)]
     pub countdown: Option<std::time::Duration>,
     /// Play a notification sound when the countdown is up
-    #[clap(short, long)]
+    #[clap(short, long, default_value_t = true)]
     pub sound: bool,
 
     // internal variables