diff --git a/dunge/src/context.rs b/dunge/src/context.rs
index 05faef0..d59bee2 100644
--- a/dunge/src/context.rs
+++ b/dunge/src/context.rs
@@ -124,11 +124,10 @@ impl Context {
         CopyBuffer::new(&self.0, size)
     }
 
-    pub async fn map_view<'a, S, R, F>(&self, view: CopyBufferView<'a>, tx: S, rx: R) -> Mapped<'a>
+    pub async fn map_view<'a, S, R>(&self, view: CopyBufferView<'a>, tx: S, rx: R) -> Mapped<'a>
     where
         S: FnOnce(MapResult) + wgpu::WasmNotSend + 'static,
-        R: FnOnce() -> F,
-        F: IntoFuture<Output = MapResult>,
+        R: IntoFuture<Output = MapResult>,
     {
         view.map(&self.0, tx, rx).await
     }
diff --git a/dunge/src/texture.rs b/dunge/src/texture.rs
index 1eb96f9..42fa8fb 100644
--- a/dunge/src/texture.rs
+++ b/dunge/src/texture.rs
@@ -305,17 +305,16 @@ pub type MapResult = Result<(), BufferAsyncError>;
 pub struct CopyBufferView<'a>(BufferSlice<'a>);
 
 impl<'a> CopyBufferView<'a> {
-    pub(crate) async fn map<S, R, F>(self, state: &State, tx: S, rx: R) -> Mapped<'a>
+    pub(crate) async fn map<S, R>(self, state: &State, tx: S, rx: R) -> Mapped<'a>
     where
         S: FnOnce(MapResult) + WasmNotSend + 'static,
-        R: FnOnce() -> F,
-        F: IntoFuture<Output = MapResult>,
+        R: IntoFuture<Output = MapResult>,
     {
         use wgpu::*;
 
         self.0.map_async(MapMode::Read, tx);
         state.device().poll(Maintain::Wait);
-        if let Err(err) = rx().await {
+        if let Err(err) = rx.await {
             panic!("failed to copy texture: {err}");
         }
 
diff --git a/helpers/src/channel.rs b/helpers/src/channel.rs
index 1d58f8f..375fa04 100644
--- a/helpers/src/channel.rs
+++ b/helpers/src/channel.rs
@@ -1,7 +1,7 @@
 use std::{future::Future, pin::Pin};
 
 type Sender<T> = Box<dyn FnOnce(T) + Send>;
-type Receiver<T> = Box<dyn FnOnce() -> Pin<Box<dyn Future<Output = T>>>>;
+type Receiver<T> = Pin<Box<dyn Future<Output = T>>>;
 
 pub fn oneshot<T>() -> (Sender<T>, Receiver<T>)
 where
@@ -10,6 +10,6 @@ where
     let (tx, rx) = async_channel::bounded(1);
     (
         Box::new(move |r| tx.send_blocking(r).expect("send mapped result")),
-        Box::new(|| Box::pin(async move { rx.recv().await.expect("recv mapped result") })),
+        Box::pin(async move { rx.recv().await.expect("recv mapped result") }),
     )
 }