diff --git a/src/plumbing.rs b/src/plumbing.rs
index 01a909a9..66428332 100644
--- a/src/plumbing.rs
+++ b/src/plumbing.rs
@@ -49,7 +49,7 @@ pub trait QueryStorageMassOps<DB: Database> {
     fn sweep(&self, db: &DB, strategy: SweepStrategy);
 }
 
-pub trait DatabaseKey<DB>: Clone + Debug + Eq + Hash + Send + Sync {
+pub trait DatabaseKey<DB>: Clone + Debug + Eq + Hash {
     /// Returns true if the value of this query may have changed since
     /// the given revision.
     fn maybe_changed_since(&self, db: &DB, revision: Revision) -> bool;