diff --git a/devtools/src/time_machine.rs b/devtools/src/time_machine.rs
index 3c8c18a7..e9e51874 100644
--- a/devtools/src/time_machine.rs
+++ b/devtools/src/time_machine.rs
@@ -13,7 +13,7 @@ where
 impl<P> TimeMachine<P>
 where
     P: Program,
-    P::Message: std::fmt::Debug + Clone,
+    P::Message: Clone,
 {
     pub fn new() -> Self {
         Self {