diff --git a/libs/bufferstreams/rust/src/buffers/buffer_owner.rs b/libs/bufferstreams/rust/src/buffers/buffer_owner.rs
index a4abb9d..155a8bf 100644
--- a/libs/bufferstreams/rust/src/buffers/buffer_owner.rs
+++ b/libs/bufferstreams/rust/src/buffers/buffer_owner.rs
@@ -16,7 +16,7 @@
 
 /// Trait that represents an owner of a buffer that might need to handle events such as a buffer
 /// being dropped.
-pub trait BufferOwner {
+pub trait BufferOwner: Send + Sync {
     /// Called when a buffer is dropped.
     fn on_return(&self, buffer: &Buffer);
 }