diff --git a/src/closures/exercise.rs b/src/closures/exercise.rs
index e6951257b128..01c71f801891 100644
--- a/src/closures/exercise.rs
+++ b/src/closures/exercise.rs
@@ -30,9 +30,6 @@ impl Logger for StderrLogger {
 
 /// Only log messages matching a filtering predicate.
 struct Filter<L, P>
-where
-    L: Logger,
-    P: Fn(u8, &str) -> bool,
 {
     inner: L,
     predicate: P,