diff --git a/candle-examples/examples/segment-anything/main.rs b/candle-examples/examples/segment-anything/main.rs
index 911442a5..10f65c66 100644
--- a/candle-examples/examples/segment-anything/main.rs
+++ b/candle-examples/examples/segment-anything/main.rs
@@ -39,7 +39,7 @@ struct Args {
 
     /// The detection threshold for the mask, 0 is the default value, negative values mean a larger
     /// mask, positive makes the mask more selective.
-    #[arg(long, default_value_t = 0.)]
+    #[arg(long, allow_hyphen_values = true, default_value_t = 0.)]
     threshold: f32,
 
     /// Enable tracing (generates a trace-timestamp.json file).