diff --git a/src/flow/binary.rs b/src/flow/binary.rs
index 113f999..a7aa556 100644
--- a/src/flow/binary.rs
+++ b/src/flow/binary.rs
@@ -18,10 +18,10 @@ pub type KeySplit<'a, BT> = (<BT as BinaryTrees<'a>>::Tree, <BT as BinaryTrees<'
 pub type BTWrap<'a, BT, A> = WrapC<'a, A, BT>;
 
 pub trait BinaryTrees<'a>: FunctorContext<'a, T = Self::_Tm> + Clone {
-    type Node: 'a + Send;
-    type Reference: 'a + Send;
-    type Tree: 'a + Send;
-    type Key: 'a + Send + Clone;
+    type Node: Send;
+    type Reference: Send;
+    type Tree: Send;
+    type Key: Send + Clone;
     type Comparator: Comparator<Self::Key>;
 
     type _Tm: Monad<'a>;