diff --git a/src/agent.rs b/src/agent.rs
index c2fc1c9..c53876a 100644
--- a/src/agent.rs
+++ b/src/agent.rs
@@ -43,7 +43,7 @@ pub struct AgentBuilder {
     #[cfg(feature = "cookies")]
     cookie_store: Option<CookieStore>,
     resolver: ArcResolver,
-    middleware: Vec<Box<dyn Middleware + Send + Sync>>,
+    middleware: Vec<Box<dyn Middleware>>,
 }
 
 /// Config as built by AgentBuilder and then static for the lifetime of the Agent.
@@ -111,7 +111,7 @@ pub(crate) struct AgentState {
     #[cfg(feature = "cookies")]
     pub(crate) cookie_tin: CookieTin,
     pub(crate) resolver: ArcResolver,
-    pub(crate) middleware: Vec<Box<dyn Middleware + Send + Sync>>,
+    pub(crate) middleware: Vec<Box<dyn Middleware>>,
 }
 
 impl Agent {
@@ -601,7 +601,7 @@ impl AgentBuilder {
     ///
     /// All requests made by the agent will use this middleware. Middleware is invoked
     /// in the order they are added to the builder.
-    pub fn middleware(mut self, m: impl Middleware + Send + Sync + 'static) -> Self {
+    pub fn middleware(mut self, m: impl Middleware) -> Self {
         self.middleware.push(Box::new(m));
         self
     }
diff --git a/src/middleware.rs b/src/middleware.rs
index ff6c2fc..a1b8fe8 100644
--- a/src/middleware.rs
+++ b/src/middleware.rs
@@ -126,7 +126,7 @@ use crate::{Error, Request, Response};
 ///
 /// # Ok(()) }
 /// ```
-pub trait Middleware {
+pub trait Middleware: Send + Sync + 'static {
     /// Handle of the middleware logic.
     fn handle(&self, request: Request, next: MiddlewareNext) -> Result<Response, Error>;
 }
@@ -158,7 +158,7 @@ impl<'a> MiddlewareNext<'a> {
 
 impl<F> Middleware for F
 where
-    F: Fn(Request, MiddlewareNext) -> Result<Response, Error>,
+    F: Fn(Request, MiddlewareNext) -> Result<Response, Error> + Send + Sync + 'static,
 {
     fn handle(&self, request: Request, next: MiddlewareNext) -> Result<Response, Error> {
         (self)(request, next)
diff --git a/src/request.rs b/src/request.rs
index fc506f0..42eb455 100644
--- a/src/request.rs
+++ b/src/request.rs
@@ -7,8 +7,8 @@ use crate::body::Payload;
 use crate::header::{self, Header};
 use crate::middleware::MiddlewareNext;
 use crate::unit::{self, Unit};
+use crate::Response;
 use crate::{agent::Agent, error::Error};
-use crate::{Middleware, Response};
 
 pub type Result<T> = std::result::Result<T, Error>;
 
@@ -143,11 +143,7 @@ impl Request {
         let response = if !self.agent.state.middleware.is_empty() {
             // Clone agent to get a local copy with same lifetime as Payload
             let agent = self.agent.clone();
-            let chain = &mut agent
-                .state
-                .middleware
-                .iter()
-                .map(|mw| mw.as_ref() as &dyn Middleware);
+            let chain = &mut agent.state.middleware.iter().map(|mw| mw.as_ref());
 
             let request_fn = Box::new(request_fn);