diff --git a/reqwest-middleware/src/client.rs b/reqwest-middleware/src/client.rs
index 15145cc..21d51a1 100644
--- a/reqwest-middleware/src/client.rs
+++ b/reqwest-middleware/src/client.rs
@@ -247,6 +247,7 @@ impl fmt::Debug for ClientWithMiddleware {
     }
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 mod service {
     use std::{
         future::Future,
@@ -422,6 +423,7 @@ impl RequestBuilder {
     /// The timeout is applied from when the request starts connecting until the
     /// response body has finished. It affects only this request and overrides
     /// the timeout configured using `ClientBuilder::timeout()`.
+    #[cfg(not(target_arch = "wasm32"))]
     pub fn timeout(self, timeout: std::time::Duration) -> Self {
         RequestBuilder {
             inner: self.inner.timeout(timeout),