diff --git a/src/launcher.rs b/src/launcher.rs
index af3640b..77a1ddb 100644
--- a/src/launcher.rs
+++ b/src/launcher.rs
@@ -12,9 +12,9 @@ pub mod batcher;
 
 pub struct Launcher<Cushion, UIT, UIContext>
 where
-    UIT: UI<Context = UIContext>,
+    UIT: UI<Cushion, Context = UIContext>,
     UIContext: Send,
-    Cushion: Sync + Send,
+    Cushion: Sync + Send + 'static,
 {
     batcher: Batcher<Cushion, UIContext>,
 
@@ -24,7 +24,7 @@ where
 
 impl<Cushion, UIT, UIContext> Default for Launcher<Cushion, UIT, UIContext>
 where
-    UIT: UI<Context = UIContext>,
+    UIT: UI<Cushion, Context = UIContext>,
     UIContext: Send,
     Cushion: Sync + Send,
 {
@@ -51,7 +51,7 @@ where
 /// as the transformer function
 impl<Cushion, UIT, UIContext> Launcher<Cushion, UIT, UIContext>
 where
-    UIT: UI<Context = UIContext>,
+    UIT: UI<Cushion, Context = UIContext>,
     UIContext: Send,
     Cushion: Send + Sync + 'static,
 {
diff --git a/src/ui.rs b/src/ui.rs
index aa3a4f5..2cddeba 100644
--- a/src/ui.rs
+++ b/src/ui.rs
@@ -1,9 +1,9 @@
 use color_eyre::Result;
 
-pub trait UI {
+pub trait UI<Cushion: Send + Sync + 'static> {
     type Context;
 
-    fn run<Cushion: Send>(
+    fn run(
         &self,
         batcher: crate::launcher::batcher::Batcher<Cushion, Self::Context>,
     ) -> impl std::future::Future<Output = Result<Option<Cushion>>> + Send;
diff --git a/tests/dummyui.rs b/tests/dummyui.rs
index 605d533..0d90147 100644
--- a/tests/dummyui.rs
+++ b/tests/dummyui.rs
@@ -29,17 +29,15 @@ where
     }
 }
 
-impl<T, F> UI for DummyUI<T, F>
+impl<T, F, Cushion> UI<Cushion> for DummyUI<T, F>
 where
     T: Sync + Send,
     F: Fn(&T) + Sync,
+    Cushion: Send + Sync + 'static,
 {
     type Context = T;
 
-    async fn run<Cushion: Send>(
-        &self,
-        mut batcher: Batcher<Cushion, Self::Context>,
-    ) -> Result<Option<Cushion>> {
+    async fn run(&self, mut batcher: Batcher<Cushion, Self::Context>) -> Result<Option<Cushion>> {
         let mut more = true;
         let mut buf: Buffer<(T, usize)> = Buffer::default();