diff --git a/benchmark/src/main.rs b/benchmark/src/main.rs
index f32b1ad4..67889e85 100644
--- a/benchmark/src/main.rs
+++ b/benchmark/src/main.rs
@@ -96,7 +96,7 @@ struct Args {
 
     /// Generation parameter in case you want to specifically test/debug particular
     /// decoding strategies, for full doc refer to the `text-generation-server`
-    #[clap(default_values_t="vec![]", long, env)]
+    #[clap(long, env, value_parser=parse_key_val::<String, f32>)]
     logit_bias: Vec<(String, f32)>,
 }
 
@@ -125,6 +125,8 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         logit_bias,
     } = args;
 
+    dbg!(&logit_bias);
+
     let batch_size = batch_size.unwrap_or(vec![1, 2, 4, 8, 16, 32]);
 
     // Tokenizer instance
@@ -213,3 +215,18 @@ fn init_logging() {
         .with(fmt_layer)
         .init();
 }
+
+// Taken from https://github.com/clap-rs/clap/blob/master/examples/typed-derive.rs#L48
+// Used to parse LogitBias's
+pub(crate) fn parse_key_val<T, U>(s: &str) -> Result<(T, U), Box<dyn std::error::Error + Send + Sync + 'static>>
+    where
+        T: std::str::FromStr,
+        T::Err: std::error::Error + Send + Sync + 'static,
+        U: std::str::FromStr,
+        U::Err: std::error::Error + Send + Sync + 'static,
+{
+    let pos = s
+        .find('=')
+        .ok_or_else(|| format!("invalid KEY=value: no `=` found in `{s}`"))?;
+    Ok((s[..pos].parse()?, s[pos + 1..].parse()?))
+}
\ No newline at end of file