diff --git a/system_zero/Cargo.toml b/system_zero/Cargo.toml
index f1cb5729..458ce27a 100644
--- a/system_zero/Cargo.toml
+++ b/system_zero/Cargo.toml
@@ -5,7 +5,7 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
-plonky2 = { path = "../plonky2" }
+plonky2 = { path = "../plonky2", features = ["timing"] }
 plonky2_util = { path = "../util" }
 starky = { path = "../starky" }
 anyhow = "1.0.40"
diff --git a/system_zero/src/system_zero.rs b/system_zero/src/system_zero.rs
index 19c2df8c..41d39cf7 100644
--- a/system_zero/src/system_zero.rs
+++ b/system_zero/src/system_zero.rs
@@ -69,7 +69,7 @@ impl<F: RichField + Extendable<D>, const D: usize> SystemZero<F, D> {
     }
 
     pub fn generate_trace(&self) -> Vec<PolynomialValues<F>> {
-        let mut timing = TimingTree::new("generate trace", log::Level::Debug);
+        let timing = TimingTree::new("generate trace", log::Level::Debug);
 
         // Generate the witness, except for permuted columns in the lookup argument.
         let trace_rows = timed!(