diff --git a/tank-rust/src/dqn/collect.rs b/tank-rust/src/dqn/collect.rs
index e1074b3..43aa721 100644
--- a/tank-rust/src/dqn/collect.rs
+++ b/tank-rust/src/dqn/collect.rs
@@ -16,6 +16,7 @@ pub struct App<'a> {
     last_state_action: Option<(Info<'a>, Action)>,
     #[cfg(feature = "train")]
     outlet: BufWriter<File>,
+    #[cfg(feature = "train")]
     explore_rate: f32,
 }