diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e9fcdcc..8f519e5 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -58,6 +58,14 @@ jobs:
       with:
         command:  check
         args: --features unstable --all --bins --examples --tests
+        
+    - name: check wasm
+      uses: actions-rs/cargo@v1
+      with:
+        command:  check
+        target: wasm32-unknown-unknown
+        override: true
+        args: --features unstable --all --bins --tests
 
     - name: check bench
       uses: actions-rs/cargo@v1
diff --git a/Cargo.toml b/Cargo.toml
index dffdc5c..e74a2ed 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -63,14 +63,25 @@ once_cell = { version = "1.3.1", optional = true }
 pin-project-lite = { version = "0.1.4", optional = true }
 pin-utils = { version = "0.1.0-alpha.4", optional = true }
 slab = { version = "0.4.2", optional = true }
+
+[target.'cfg(not(target_os = "unknown"))'.dependencies]
 smol = { path = "../smol", optional = true }
 
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+wasm-timer = "0.2.4"
+wasm-bindgen-futures = "0.4.10"
+futures-channel = "0.3.4"
+
+[target.'cfg(target_arch = "wasm32")'.dev-dependencies]
+wasm-bindgen-test = "0.3.10"
+
 [dev-dependencies]
 femme = "1.3.0"
 rand = "0.7.3"
 surf = "1.0.3"
 tempdir = "0.3.7"
 futures = "0.3.4"
+rand_xorshift = "0.2.0"
 
 [[test]]
 name = "stream"
diff --git a/src/future/future/delay.rs b/src/future/future/delay.rs
index e194470..b6c30bc 100644
--- a/src/future/future/delay.rs
+++ b/src/future/future/delay.rs
@@ -3,9 +3,9 @@ use std::pin::Pin;
 use std::time::Duration;
 
 use pin_project_lite::pin_project;
-use smol::Timer;
 
 use crate::task::{Context, Poll};
+use crate::utils::Timer;
 
 pin_project! {
     #[doc(hidden)]
diff --git a/src/future/timeout.rs b/src/future/timeout.rs
index ec547f8..4a9d93c 100644
--- a/src/future/timeout.rs
+++ b/src/future/timeout.rs
@@ -5,9 +5,9 @@ use std::pin::Pin;
 use std::time::Duration;
 
 use pin_project_lite::pin_project;
-use smol::Timer;
 
 use crate::task::{Context, Poll};
+use crate::utils::Timer;
 
 /// Awaits a future or times out after a duration of time.
 ///
diff --git a/src/io/mod.rs b/src/io/mod.rs
index dd97567..f5dd9e2 100644
--- a/src/io/mod.rs
+++ b/src/io/mod.rs
@@ -307,22 +307,33 @@ cfg_std! {
 cfg_default! {
     // For use in the print macros.
     #[doc(hidden)]
+    #[cfg(not(target_os = "unknown"))]
     pub use stdio::{_eprint, _print};
 
+    #[cfg(not(target_os = "unknown"))]
     pub use stderr::{stderr, Stderr};
+    #[cfg(not(target_os = "unknown"))]
     pub use stdin::{stdin, Stdin};
+    #[cfg(not(target_os = "unknown"))]
     pub use stdout::{stdout, Stdout};
     pub use timeout::timeout;
 
     mod timeout;
+    #[cfg(not(target_os = "unknown"))]
     mod stderr;
+    #[cfg(not(target_os = "unknown"))]
     mod stdin;
+    #[cfg(not(target_os = "unknown"))]
     mod stdio;
+    #[cfg(not(target_os = "unknown"))]
     mod stdout;
 }
 
 cfg_unstable_default! {
+    #[cfg(not(target_os = "unknown"))]
     pub use stderr::StderrLock;
+    #[cfg(not(target_os = "unknown"))]
     pub use stdin::StdinLock;
+    #[cfg(not(target_os = "unknown"))]
     pub use stdout::StdoutLock;
 }
diff --git a/src/io/read/mod.rs b/src/io/read/mod.rs
index 8aade18..0d42920 100644
--- a/src/io/read/mod.rs
+++ b/src/io/read/mod.rs
@@ -17,9 +17,9 @@ use std::mem;
 
 use crate::io::IoSliceMut;
 
-pub use take::Take;
 pub use bytes::Bytes;
 pub use chain::Chain;
+pub use take::Take;
 
 extension_trait! {
     use std::pin::Pin;
@@ -483,7 +483,7 @@ mod tests {
     use crate::prelude::*;
 
     #[test]
-    fn test_read_by_ref() -> io::Result<()> {
+    fn test_read_by_ref() {
         crate::task::block_on(async {
             let mut f = io::Cursor::new(vec![0u8, 1, 2, 3, 4, 5, 6, 7, 8]);
             let mut buffer = Vec::new();
@@ -493,14 +493,13 @@ mod tests {
                 let reference = f.by_ref();
 
                 // read at most 5 bytes
-                assert_eq!(reference.take(5).read_to_end(&mut buffer).await?, 5);
+                assert_eq!(reference.take(5).read_to_end(&mut buffer).await.unwrap(), 5);
                 assert_eq!(&buffer, &[0, 1, 2, 3, 4])
             } // drop our &mut reference so we can use f again
 
             // original file still usable, read the rest
-            assert_eq!(f.read_to_end(&mut other_buffer).await?, 4);
+            assert_eq!(f.read_to_end(&mut other_buffer).await.unwrap(), 4);
             assert_eq!(&other_buffer, &[5, 6, 7, 8]);
-            Ok(())
-        })
+        });
     }
 }
diff --git a/src/io/read/take.rs b/src/io/read/take.rs
index 09b02c2..ba9a9e3 100644
--- a/src/io/read/take.rs
+++ b/src/io/read/take.rs
@@ -218,7 +218,7 @@ impl<T: BufRead> BufRead for Take<T> {
     }
 }
 
-#[cfg(test)]
+#[cfg(all(test, not(target_os = "unknown")))]
 mod tests {
     use crate::io;
     use crate::prelude::*;
diff --git a/src/io/timeout.rs b/src/io/timeout.rs
index c19d25d..ce33fea 100644
--- a/src/io/timeout.rs
+++ b/src/io/timeout.rs
@@ -4,9 +4,9 @@ use std::task::{Context, Poll};
 use std::time::Duration;
 
 use pin_project_lite::pin_project;
-use smol::Timer;
 
 use crate::io;
+use crate::utils::Timer;
 
 /// Awaits an I/O future or times out after a duration of time.
 ///
diff --git a/src/lib.rs b/src/lib.rs
index 7e0e98d..408a7ab 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -267,14 +267,17 @@ cfg_std! {
 }
 
 cfg_default! {
+    #[cfg(not(target_os = "unknown"))]
     pub mod fs;
     pub mod path;
     pub mod net;
+    #[cfg(not(target_os = "unknown"))]
     pub(crate) mod rt;
 }
 
 cfg_unstable! {
     pub mod pin;
+    #[cfg(not(target_os = "unknown"))]
     pub mod process;
 
     mod unit;
diff --git a/src/net/mod.rs b/src/net/mod.rs
index fe83d3b..1814073 100644
--- a/src/net/mod.rs
+++ b/src/net/mod.rs
@@ -61,10 +61,16 @@ pub use std::net::Shutdown;
 pub use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
 pub use std::net::{SocketAddr, SocketAddrV4, SocketAddrV6};
 
+#[cfg(not(target_os = "unknown"))]
 pub use addr::ToSocketAddrs;
+#[cfg(not(target_os = "unknown"))]
 pub use tcp::{Incoming, TcpListener, TcpStream};
+#[cfg(not(target_os = "unknown"))]
 pub use udp::UdpSocket;
 
+#[cfg(not(target_os = "unknown"))]
 mod addr;
+#[cfg(not(target_os = "unknown"))]
 mod tcp;
+#[cfg(not(target_os = "unknown"))]
 mod udp;
diff --git a/src/path/path.rs b/src/path/path.rs
index dfe9426..185bfaf 100644
--- a/src/path/path.rs
+++ b/src/path/path.rs
@@ -4,9 +4,9 @@ use std::ffi::{OsStr, OsString};
 use std::rc::Rc;
 use std::sync::Arc;
 
-use crate::fs;
-use crate::io;
 use crate::path::{Ancestors, Components, Display, Iter, PathBuf, StripPrefixError};
+#[cfg(not(target_os = "unknown"))]
+use crate::{fs, io};
 
 /// A slice of a path.
 ///
@@ -584,6 +584,7 @@ impl Path {
     /// #
     /// # Ok(()) }) }
     /// ```
+    #[cfg(not(target_os = "unknown"))]
     pub async fn metadata(&self) -> io::Result<fs::Metadata> {
         fs::metadata(self).await
     }
@@ -607,6 +608,7 @@ impl Path {
     /// #
     /// # Ok(()) }) }
     /// ```
+    #[cfg(not(target_os = "unknown"))]
     pub async fn symlink_metadata(&self) -> io::Result<fs::Metadata> {
         fs::symlink_metadata(self).await
     }
@@ -632,6 +634,7 @@ impl Path {
     /// #
     /// # Ok(()) }) }
     /// ```
+    #[cfg(not(target_os = "unknown"))]
     pub async fn canonicalize(&self) -> io::Result<PathBuf> {
         fs::canonicalize(self).await
     }
@@ -654,6 +657,7 @@ impl Path {
     /// #
     /// # Ok(()) }) }
     /// ```
+    #[cfg(not(target_os = "unknown"))]
     pub async fn read_link(&self) -> io::Result<PathBuf> {
         fs::read_link(self).await
     }
@@ -688,6 +692,7 @@ impl Path {
     /// #
     /// # Ok(()) }) }
     /// ```
+    #[cfg(not(target_os = "unknown"))]
     pub async fn read_dir(&self) -> io::Result<fs::ReadDir> {
         fs::read_dir(self).await
     }
@@ -717,6 +722,7 @@ impl Path {
     /// check errors, call [fs::metadata].
     ///
     /// [fs::metadata]: ../fs/fn.metadata.html
+    #[cfg(not(target_os = "unknown"))]
     pub async fn exists(&self) -> bool {
         fs::metadata(self).await.is_ok()
     }
@@ -749,6 +755,7 @@ impl Path {
     ///
     /// [fs::metadata]: ../fs/fn.metadata.html
     /// [fs::Metadata::is_file]: ../fs/struct.Metadata.html#method.is_file
+    #[cfg(not(target_os = "unknown"))]
     pub async fn is_file(&self) -> bool {
         fs::metadata(self)
             .await
@@ -785,6 +792,7 @@ impl Path {
     ///
     /// [fs::metadata]: ../fs/fn.metadata.html
     /// [fs::Metadata::is_dir]: ../fs/struct.Metadata.html#method.is_dir
+    #[cfg(not(target_os = "unknown"))]
     pub async fn is_dir(&self) -> bool {
         fs::metadata(self)
             .await
diff --git a/src/stream/interval.rs b/src/stream/interval.rs
index fe249fb..4e5c92b 100644
--- a/src/stream/interval.rs
+++ b/src/stream/interval.rs
@@ -4,7 +4,7 @@ use std::task::{Context, Poll};
 use std::time::Duration;
 
 use crate::stream::Stream;
-use smol::Timer;
+use crate::utils::Timer;
 
 /// Creates a new stream that yields at a set interval.
 ///
diff --git a/src/stream/stream/delay.rs b/src/stream/stream/delay.rs
index 754bef8..0ba42b0 100644
--- a/src/stream/stream/delay.rs
+++ b/src/stream/stream/delay.rs
@@ -3,10 +3,10 @@ use core::pin::Pin;
 use core::time::Duration;
 
 use pin_project_lite::pin_project;
-use smol::Timer;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
+use crate::utils::Timer;
 
 pin_project! {
     #[doc(hidden)]
diff --git a/src/stream/stream/throttle.rs b/src/stream/stream/throttle.rs
index 4d4cc87..2f9333a 100644
--- a/src/stream/stream/throttle.rs
+++ b/src/stream/stream/throttle.rs
@@ -3,10 +3,10 @@ use std::pin::Pin;
 use std::time::Duration;
 
 use pin_project_lite::pin_project;
-use smol::Timer;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
+use crate::utils::Timer;
 
 pin_project! {
     /// A stream that only yields one element once every `duration`.
diff --git a/src/stream/stream/timeout.rs b/src/stream/stream/timeout.rs
index f49aed3..28e52ae 100644
--- a/src/stream/stream/timeout.rs
+++ b/src/stream/stream/timeout.rs
@@ -5,10 +5,10 @@ use std::pin::Pin;
 use std::time::Duration;
 
 use pin_project_lite::pin_project;
-use smol::Timer;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
+use crate::utils::Timer;
 
 pin_project! {
     /// A stream with timeout time set
diff --git a/src/sync/barrier.rs b/src/sync/barrier.rs
index 2822d54..86e9a2d 100644
--- a/src/sync/barrier.rs
+++ b/src/sync/barrier.rs
@@ -202,7 +202,7 @@ impl BarrierWaitResult {
     }
 }
 
-#[cfg(test)]
+#[cfg(all(test, not(target_os = "unknown")))]
 mod test {
     use futures::channel::mpsc::unbounded;
     use futures::sink::SinkExt;
diff --git a/src/task/block_on.rs b/src/task/block_on.rs
index 92a1187..fa66f91 100644
--- a/src/task/block_on.rs
+++ b/src/task/block_on.rs
@@ -25,9 +25,20 @@ use crate::task::Builder;
 ///     })
 /// }
 /// ```
+#[cfg(not(target_os = "unknown"))]
 pub fn block_on<F, T>(future: F) -> T
 where
     F: Future<Output = T>,
 {
     Builder::new().blocking(future)
 }
+
+/// Spawns a task and waits for it to finish.
+#[cfg(target_os = "unknown")]
+pub fn block_on<F, T>(future: F)
+where
+    F: Future<Output = T> + 'static,
+    T: 'static,
+{
+    Builder::new().local(future).unwrap();
+}
diff --git a/src/task/builder.rs b/src/task/builder.rs
index f1bf791..f48b6b4 100644
--- a/src/task/builder.rs
+++ b/src/task/builder.rs
@@ -3,7 +3,6 @@ use std::pin::Pin;
 use std::sync::Arc;
 use std::task::{Context, Poll};
 
-use kv_log_macro::trace;
 use pin_project_lite::pin_project;
 
 use crate::io;
@@ -38,15 +37,16 @@ impl Builder {
         // Create a new task handle.
         let task = Task::new(name);
 
+        #[cfg(not(target_os = "unknown"))]
         once_cell::sync::Lazy::force(&crate::rt::RUNTIME);
 
         let tag = TaskLocalsWrapper::new(task.clone());
 
-        // FIXME: do not require all futures to be boxed.
         SupportTaskLocals { tag, future }
     }
 
     /// Spawns a task with the configured settings.
+    #[cfg(not(target_os = "unknown"))]
     pub fn spawn<F, T>(self, future: F) -> io::Result<JoinHandle<T>>
     where
         F: Future<Output = T> + Send + 'static,
@@ -61,6 +61,7 @@ impl Builder {
     }
 
     /// Spawns a task locally with the configured settings.
+    #[cfg(not(target_os = "unknown"))]
     pub fn local<F, T>(self, future: F) -> io::Result<JoinHandle<T>>
     where
         F: Future<Output = T> + 'static,
@@ -74,7 +75,29 @@ impl Builder {
         Ok(JoinHandle::new(smol_task, task))
     }
 
+    /// Spawns a task locally with the configured settings.
+    #[cfg(target_arch = "wasm32")]
+    pub fn local<F, T>(self, future: F) -> io::Result<JoinHandle<T>>
+    where
+        F: Future<Output = T> + 'static,
+        T: 'static,
+    {
+        use futures_channel::oneshot::channel;
+        let (sender, receiver) = channel();
+
+        let wrapped = self.build(async move {
+            let res = future.await;
+            let _ = sender.send(res);
+        });
+
+        let task = wrapped.tag.task().clone();
+        wasm_bindgen_futures::spawn_local(wrapped);
+
+        Ok(JoinHandle::new(receiver, task))
+    }
+
     /// Spawns a task with the configured settings, blocking on its execution.
+    #[cfg(not(target_os = "unknown"))]
     pub fn blocking<F, T>(self, future: F) -> T
     where
         F: Future<Output = T>,
@@ -82,7 +105,7 @@ impl Builder {
         let wrapped = self.build(future);
 
         // Log this `block_on` operation.
-        trace!("block_on", {
+        kv_log_macro::trace!("block_on", {
             task_id: wrapped.tag.id().0,
             parent_task_id: TaskLocalsWrapper::get_current(|t| t.id().0).unwrap_or(0),
         });
diff --git a/src/task/join_handle.rs b/src/task/join_handle.rs
index 3a63271..110b827 100644
--- a/src/task/join_handle.rs
+++ b/src/task/join_handle.rs
@@ -13,13 +13,18 @@ use crate::task::{Context, Poll, Task};
 /// [spawned]: fn.spawn.html
 #[derive(Debug)]
 pub struct JoinHandle<T> {
-    handle: Option<async_task::JoinHandle<T, ()>>,
+    handle: Option<InnerHandle<T>>,
     task: Task,
 }
 
+#[cfg(not(target_os = "unknown"))]
+type InnerHandle<T> = async_task::JoinHandle<T, ()>;
+#[cfg(target_arch = "wasm32")]
+type InnerHandle<T> = futures_channel::oneshot::Receiver<T>;
+
 impl<T> JoinHandle<T> {
     /// Creates a new `JoinHandle`.
-    pub(crate) fn new(inner: async_task::JoinHandle<T, ()>, task: Task) -> JoinHandle<T> {
+    pub(crate) fn new(inner: InnerHandle<T>, task: Task) -> JoinHandle<T> {
         JoinHandle {
             handle: Some(inner),
             task,
@@ -46,11 +51,20 @@ impl<T> JoinHandle<T> {
     }
 
     /// Cancel this task.
+    #[cfg(not(target_os = "unknown"))]
     pub async fn cancel(mut self) -> Option<T> {
         let handle = self.handle.take().unwrap();
         handle.cancel();
         handle.await
     }
+
+    /// Cancel this task.
+    #[cfg(target_arch = "wasm32")]
+    pub async fn cancel(mut self) -> Option<T> {
+        let mut handle = self.handle.take().unwrap();
+        handle.close();
+        handle.await.ok()
+    }
 }
 
 impl<T> Future for JoinHandle<T> {
diff --git a/src/task/mod.rs b/src/task/mod.rs
index f5bc864..6a142ff 100644
--- a/src/task/mod.rs
+++ b/src/task/mod.rs
@@ -138,6 +138,7 @@ cfg_default! {
     pub use task_id::TaskId;
     pub use join_handle::JoinHandle;
     pub use sleep::sleep;
+    #[cfg(not(target_os = "unknown"))]
     pub use spawn::spawn;
     pub use spawn_local::spawn_local;
     pub use task_local::{AccessError, LocalKey};
@@ -150,7 +151,9 @@ cfg_default! {
     mod current;
     mod join_handle;
     mod sleep;
+    #[cfg(not(target_os = "unknown"))]
     mod spawn;
+    #[cfg(not(target_os = "unknown"))]
     mod spawn_blocking;
     mod spawn_local;
     mod task;
@@ -158,8 +161,10 @@ cfg_default! {
     mod task_local;
     mod task_locals_wrapper;
 
+    #[cfg(not(target_os = "unknown"))]
     #[cfg(any(feature = "unstable", test))]
     pub use spawn_blocking::spawn_blocking;
+    #[cfg(not(target_os = "unknown"))]
     #[cfg(not(any(feature = "unstable", test)))]
     pub(crate) use spawn_blocking::spawn_blocking;
 }
diff --git a/src/utils.rs b/src/utils.rs
index 33e6604..2ae5488 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -59,6 +59,37 @@ pub(crate) trait Context {
     fn context(self, message: impl Fn() -> String) -> Self;
 }
 
+#[cfg(not(target_os = "unknown"))]
+pub(crate) type Timer = smol::Timer;
+
+#[cfg(target_arch = "wasm32")]
+#[derive(Debug)]
+pub(crate) struct Timer(wasm_timer::Delay);
+
+#[cfg(target_arch = "wasm32")]
+impl Timer {
+    pub(crate) fn after(dur: std::time::Duration) -> Self {
+        Timer(wasm_timer::Delay::new(dur))
+    }
+}
+
+#[cfg(target_arch = "wasm32")]
+use std::pin::Pin;
+#[cfg(target_arch = "wasm32")]
+use std::task::Poll;
+
+#[cfg(target_arch = "wasm32")]
+impl std::future::Future for Timer {
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut std::task::Context<'_>) -> Poll<Self::Output> {
+        match Pin::new(&mut self.0).poll(cx) {
+            Poll::Pending => Poll::Pending,
+            Poll::Ready(_) => Poll::Ready(()),
+        }
+    }
+}
+
 /// Defers evaluation of a block of code until the end of the scope.
 #[cfg(feature = "default")]
 #[doc(hidden)]
diff --git a/tests/addr.rs b/tests/addr.rs
index aada557..fcd5aa1 100644
--- a/tests/addr.rs
+++ b/tests/addr.rs
@@ -1,3 +1,5 @@
+#![cfg(not(target_os = "unknown"))]
+
 use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6};
 
 use async_std::net::ToSocketAddrs;
diff --git a/tests/block_on.rs b/tests/block_on.rs
index c422d06..28902b0 100644
--- a/tests/block_on.rs
+++ b/tests/block_on.rs
@@ -1,3 +1,5 @@
+#![cfg(not(target_os = "unknown"))]
+
 use async_std::task;
 
 #[test]
diff --git a/tests/buf_writer.rs b/tests/buf_writer.rs
index 5df90e0..442cf8a 100644
--- a/tests/buf_writer.rs
+++ b/tests/buf_writer.rs
@@ -2,15 +2,19 @@ use async_std::io::{self, BufWriter, SeekFrom};
 use async_std::prelude::*;
 use async_std::task;
 
+#[cfg(target_arch = "wasm32")]
+wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
+
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn test_buffered_writer() {
     #![allow(clippy::cognitive_complexity)]
     task::block_on(async {
-        let inner = Vec::new();
-        let mut writer = BufWriter::with_capacity(2, inner);
+        let inner: Vec<u8> = Vec::new();
+        let mut writer = BufWriter::<Vec<u8>>::with_capacity(2, inner);
 
         writer.write(&[0, 1]).await.unwrap();
-        assert_eq!(writer.buffer(), []);
+        assert!(writer.buffer().is_empty());
         assert_eq!(*writer.get_ref(), [0, 1]);
 
         writer.write(&[2]).await.unwrap();
@@ -22,7 +26,7 @@ fn test_buffered_writer() {
         assert_eq!(*writer.get_ref(), [0, 1]);
 
         writer.flush().await.unwrap();
-        assert_eq!(writer.buffer(), []);
+        assert!(writer.buffer().is_empty());
         assert_eq!(*writer.get_ref(), [0, 1, 2, 3]);
 
         writer.write(&[4]).await.unwrap();
@@ -35,31 +39,33 @@ fn test_buffered_writer() {
         assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5]);
 
         writer.write(&[7, 8]).await.unwrap();
-        assert_eq!(writer.buffer(), []);
+        assert!(writer.buffer().is_empty());
         assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8]);
 
         writer.write(&[9, 10, 11]).await.unwrap();
-        assert_eq!(writer.buffer(), []);
+        assert!(writer.buffer().is_empty());
         assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]);
 
         writer.flush().await.unwrap();
-        assert_eq!(writer.buffer(), []);
+        assert!(writer.buffer().is_empty());
         assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]);
     })
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn test_buffered_writer_inner_into_inner_flushes() {
     task::block_on(async {
-        let mut w = BufWriter::with_capacity(3, Vec::new());
+        let mut w = BufWriter::with_capacity(3, Vec::<u8>::new());
         w.write(&[0, 1]).await.unwrap();
-        assert_eq!(*w.get_ref(), []);
+        assert!(w.get_ref().is_empty());
         let w = w.into_inner().await.unwrap();
         assert_eq!(w, [0, 1]);
     })
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn test_buffered_writer_seek() {
     task::block_on(async {
         let mut w = BufWriter::with_capacity(3, io::Cursor::new(Vec::new()));
diff --git a/tests/channel.rs b/tests/channel.rs
index f302906..a218ea2 100644
--- a/tests/channel.rs
+++ b/tests/channel.rs
@@ -6,13 +6,22 @@ use std::time::Duration;
 
 use async_std::sync::channel;
 use async_std::task;
-use rand::{thread_rng, Rng};
+use rand::{Rng, SeedableRng};
+
+#[cfg(not(target_os = "unknown"))]
+use async_std::task::spawn;
+#[cfg(target_os = "unknown")]
+use async_std::task::spawn_local as spawn;
+
+#[cfg(target_arch = "wasm32")]
+wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
 
 fn ms(ms: u64) -> Duration {
     Duration::from_millis(ms)
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn smoke() {
     task::block_on(async {
         let (s, r) = channel(1);
@@ -35,6 +44,7 @@ fn smoke() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn capacity() {
     for i in 1..10 {
         let (s, r) = channel::<()>(i);
@@ -44,6 +54,7 @@ fn capacity() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn len_empty_full() {
     #![allow(clippy::cognitive_complexity)]
     task::block_on(async {
@@ -86,11 +97,12 @@ fn len_empty_full() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn recv() {
     task::block_on(async {
         let (s, r) = channel(100);
 
-        task::spawn(async move {
+        spawn(async move {
             assert_eq!(r.recv().await.unwrap(), 7);
             task::sleep(ms(1000)).await;
             assert_eq!(r.recv().await.unwrap(), 8);
@@ -107,11 +119,12 @@ fn recv() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn send() {
     task::block_on(async {
         let (s, r) = channel(1);
 
-        task::spawn(async move {
+        spawn(async move {
             s.send(7).await;
             task::sleep(ms(1000)).await;
             s.send(8).await;
@@ -129,6 +142,7 @@ fn send() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn recv_after_disconnect() {
     task::block_on(async {
         let (s, r) = channel(100);
@@ -147,6 +161,7 @@ fn recv_after_disconnect() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn len() {
     const COUNT: usize = 25_000;
     const CAP: usize = 1000;
@@ -184,7 +199,7 @@ fn len() {
         assert_eq!(s.len(), 0);
         assert_eq!(r.len(), 0);
 
-        let child = task::spawn({
+        let child = spawn({
             let r = r.clone();
             async move {
                 for i in 0..COUNT {
@@ -209,11 +224,12 @@ fn len() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn disconnect_wakes_receiver() {
     task::block_on(async {
         let (s, r) = channel::<()>(1);
 
-        let child = task::spawn(async move {
+        let child = spawn(async move {
             assert!(r.recv().await.is_err());
         });
 
@@ -225,13 +241,14 @@ fn disconnect_wakes_receiver() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn spsc() {
     const COUNT: usize = 100_000;
 
     task::block_on(async {
         let (s, r) = channel(3);
 
-        let child = task::spawn(async move {
+        let child = spawn(async move {
             for i in 0..COUNT {
                 assert_eq!(r.recv().await.unwrap(), i);
             }
@@ -248,6 +265,7 @@ fn spsc() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn mpmc() {
     const COUNT: usize = 25_000;
     const TASKS: usize = 4;
@@ -262,7 +280,7 @@ fn mpmc() {
         for _ in 0..TASKS {
             let r = r.clone();
             let v = v.clone();
-            tasks.push(task::spawn(async move {
+            tasks.push(spawn(async move {
                 for _ in 0..COUNT {
                     let n = r.recv().await.unwrap();
                     v[n].fetch_add(1, Ordering::SeqCst);
@@ -272,7 +290,7 @@ fn mpmc() {
 
         for _ in 0..TASKS {
             let s = s.clone();
-            tasks.push(task::spawn(async move {
+            tasks.push(spawn(async move {
                 for i in 0..COUNT {
                     s.send(i).await;
                 }
@@ -290,6 +308,7 @@ fn mpmc() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn oneshot() {
     const COUNT: usize = 10_000;
 
@@ -297,8 +316,8 @@ fn oneshot() {
         for _ in 0..COUNT {
             let (s, r) = channel(1);
 
-            let c1 = task::spawn(async move { r.recv().await.unwrap() });
-            let c2 = task::spawn(async move { s.send(0).await });
+            let c1 = spawn(async move { r.recv().await.unwrap() });
+            let c2 = spawn(async move { s.send(0).await });
 
             c1.await;
             c2.await;
@@ -307,6 +326,7 @@ fn oneshot() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn drops() {
     const RUNS: usize = 100;
 
@@ -321,17 +341,16 @@ fn drops() {
         }
     }
 
-    let mut rng = thread_rng();
-
     for _ in 0..RUNS {
-        task::block_on(async {
+        let mut rng = rand_xorshift::XorShiftRng::seed_from_u64(0);
+        task::block_on(async move {
             let steps = rng.gen_range(0, 10_000);
             let additional = rng.gen_range(0, 50);
 
             DROPS.store(0, Ordering::SeqCst);
             let (s, r) = channel::<DropCounter>(50);
 
-            let child = task::spawn({
+            let child = spawn({
                 let r = r.clone();
                 async move {
                     for _ in 0..steps {
diff --git a/tests/condvar.rs b/tests/condvar.rs
index c4d680f..7b05b28 100644
--- a/tests/condvar.rs
+++ b/tests/condvar.rs
@@ -5,13 +5,22 @@ use std::time::Duration;
 use async_std::sync::{Condvar, Mutex};
 use async_std::task::{self, JoinHandle};
 
+#[cfg(not(target_os = "unknown"))]
+use async_std::task::spawn;
+#[cfg(target_os = "unknown")]
+use async_std::task::spawn_local as spawn;
+
+#[cfg(target_arch = "wasm32")]
+wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
+
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn wait_timeout_with_lock() {
     task::block_on(async {
         let pair = Arc::new((Mutex::new(false), Condvar::new()));
         let pair2 = pair.clone();
 
-        task::spawn(async move {
+        spawn(async move {
             let (m, c) = &*pair2;
             let _g = m.lock().await;
             task::sleep(Duration::from_millis(20)).await;
@@ -27,6 +36,7 @@ fn wait_timeout_with_lock() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn wait_timeout_without_lock() {
     task::block_on(async {
         let m = Mutex::new(false);
@@ -40,6 +50,7 @@ fn wait_timeout_without_lock() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn wait_timeout_until_timed_out() {
     task::block_on(async {
         let m = Mutex::new(false);
@@ -55,6 +66,7 @@ fn wait_timeout_until_timed_out() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn notify_all() {
     task::block_on(async {
         let mut tasks: Vec<JoinHandle<()>> = Vec::new();
@@ -62,7 +74,7 @@ fn notify_all() {
 
         for _ in 0..10 {
             let pair = pair.clone();
-            tasks.push(task::spawn(async move {
+            tasks.push(spawn(async move {
                 let (m, c) = &*pair;
                 let mut count = m.lock().await;
                 while *count == 0 {
diff --git a/tests/io_timeout.rs b/tests/io_timeout.rs
index 85a17ab..fa30a68 100644
--- a/tests/io_timeout.rs
+++ b/tests/io_timeout.rs
@@ -5,6 +5,7 @@ use async_std::task;
 
 #[test]
 #[should_panic(expected = "timed out")]
+#[cfg(not(target_os = "unknown"))]
 fn io_timeout_timedout() {
     task::block_on(async {
         io::timeout(Duration::from_secs(1), async {
diff --git a/tests/mutex.rs b/tests/mutex.rs
index ebdd752..76f42e2 100644
--- a/tests/mutex.rs
+++ b/tests/mutex.rs
@@ -5,7 +5,16 @@ use async_std::sync::Mutex;
 use async_std::task;
 use futures::channel::mpsc;
 
+#[cfg(not(target_os = "unknown"))]
+use async_std::task::spawn;
+#[cfg(target_os = "unknown")]
+use async_std::task::spawn_local as spawn;
+
+#[cfg(target_arch = "wasm32")]
+wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
+
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn smoke() {
     task::block_on(async {
         let m = Mutex::new(());
@@ -15,18 +24,21 @@ fn smoke() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn try_lock() {
     let m = Mutex::new(());
     *m.try_lock().unwrap() = ();
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn into_inner() {
     let m = Mutex::new(10);
     assert_eq!(m.into_inner(), 10);
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn get_mut() {
     let mut m = Mutex::new(10);
     *m.get_mut() = 20;
@@ -34,21 +46,21 @@ fn get_mut() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn contention() {
     task::block_on(async {
         let (tx, mut rx) = mpsc::unbounded();
 
         let tx = Arc::new(tx);
         let mutex = Arc::new(Mutex::new(0));
-        let num_tasks = 10; //000;
+        let num_tasks = 10000;
 
         let mut handles = Vec::new();
         for _ in 0..num_tasks {
             let tx = tx.clone();
             let mutex = mutex.clone();
 
-            dbg!("spawn");
-            handles.push(task::spawn(async move {
+            handles.push(spawn(async move {
                 let mut lock = mutex.lock().await;
                 *lock += 1;
                 tx.unbounded_send(()).unwrap();
@@ -56,8 +68,7 @@ fn contention() {
             }));
         }
 
-        for i in 0..num_tasks {
-            dbg!(i);
+        for _ in 0..num_tasks {
             rx.next().await.unwrap();
         }
 
diff --git a/tests/rwlock.rs b/tests/rwlock.rs
index 370dcb9..1d33a45 100644
--- a/tests/rwlock.rs
+++ b/tests/rwlock.rs
@@ -10,6 +10,14 @@ use async_std::sync::RwLock;
 use async_std::task;
 use futures::channel::mpsc;
 
+#[cfg(not(target_os = "unknown"))]
+use async_std::task::spawn;
+#[cfg(target_os = "unknown")]
+use async_std::task::spawn_local as spawn;
+
+#[cfg(target_arch = "wasm32")]
+wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
+
 /// Generates a random number in `0..n`.
 pub fn random(n: u32) -> u32 {
     thread_local! {
@@ -35,6 +43,7 @@ pub fn random(n: u32) -> u32 {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn smoke() {
     task::block_on(async {
         let lock = RwLock::new(());
@@ -46,6 +55,7 @@ fn smoke() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn try_write() {
     task::block_on(async {
         let lock = RwLock::new(0isize);
@@ -56,12 +66,14 @@ fn try_write() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn into_inner() {
     let lock = RwLock::new(10);
     assert_eq!(lock.into_inner(), 10);
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn into_inner_and_drop() {
     struct Counter(Arc<AtomicUsize>);
 
@@ -84,6 +96,7 @@ fn into_inner_and_drop() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn get_mut() {
     let mut lock = RwLock::new(10);
     *lock.get_mut() = 20;
@@ -91,6 +104,7 @@ fn get_mut() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn contention() {
     const N: u32 = 10;
     const M: usize = 1000;
@@ -104,7 +118,7 @@ fn contention() {
         let tx = tx.clone();
         let rw = rw.clone();
 
-        task::spawn(async move {
+        spawn(async move {
             for _ in 0..M {
                 if random(N) == 0 {
                     drop(rw.write().await);
@@ -116,7 +130,7 @@ fn contention() {
         });
     }
 
-    task::block_on(async {
+    task::block_on(async move {
         for _ in 0..N {
             rx.next().await.unwrap();
         }
@@ -124,6 +138,7 @@ fn contention() {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn writer_and_readers() {
     #[derive(Default)]
     struct Yield(Cell<bool>);
@@ -146,7 +161,7 @@ fn writer_and_readers() {
     let (tx, mut rx) = mpsc::unbounded();
 
     // Spawn a writer task.
-    task::spawn({
+    spawn({
         let lock = lock.clone();
         async move {
             let mut lock = lock.write().await;
@@ -164,13 +179,13 @@ fn writer_and_readers() {
     let mut readers = Vec::new();
     for _ in 0..5 {
         let lock = lock.clone();
-        readers.push(task::spawn(async move {
+        readers.push(spawn(async move {
             let lock = lock.read().await;
             assert!(*lock >= 0);
         }));
     }
 
-    task::block_on(async {
+    task::block_on(async move {
         // Wait for readers to pass their asserts.
         for r in readers {
             r.await;
diff --git a/tests/stream.rs b/tests/stream.rs
index 42a6191..3576cb9 100644
--- a/tests/stream.rs
+++ b/tests/stream.rs
@@ -8,14 +8,23 @@ use async_std::stream;
 use async_std::sync::channel;
 use async_std::task;
 
+#[cfg(target_arch = "wasm32")]
+wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
+
+#[cfg(not(target_os = "unknown"))]
+use async_std::task::spawn;
+#[cfg(target_os = "unknown")]
+use async_std::task::spawn_local as spawn;
+
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 /// Checks that streams are merged fully even if one of the components
 /// experiences delay.
 fn merging_delayed_streams_work() {
     let (sender, receiver) = channel::<i32>(10);
 
     let mut s = receiver.merge(stream::empty());
-    let t = task::spawn(async move {
+    let t = spawn(async move {
         let mut xs = Vec::new();
         while let Some(x) = s.next().await {
             xs.push(x);
@@ -34,7 +43,7 @@ fn merging_delayed_streams_work() {
     let (sender, receiver) = channel::<i32>(10);
 
     let mut s = stream::empty().merge(receiver);
-    let t = task::spawn(async move {
+    let t = spawn(async move {
         let mut xs = Vec::new();
         while let Some(x) = s.next().await {
             xs.push(x);
@@ -85,16 +94,17 @@ fn explode<S: Stream>(s: S) -> Explode<S> {
 }
 
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn merge_works_with_unfused_streams() {
     let s1 = explode(stream::once(92));
     let s2 = explode(stream::once(92));
     let mut s = s1.merge(s2);
-    let xs = task::block_on(async move {
+
+    task::block_on(async move {
         let mut xs = Vec::new();
         while let Some(x) = s.next().await {
             xs.push(x)
         }
-        xs
+        assert_eq!(xs, vec![92, 92]);
     });
-    assert_eq!(xs, vec![92, 92]);
 }
diff --git a/tests/task_local.rs b/tests/task_local.rs
index 813185c..b5345fe 100644
--- a/tests/task_local.rs
+++ b/tests/task_local.rs
@@ -3,7 +3,16 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use async_std::task;
 use async_std::task_local;
 
+#[cfg(not(target_os = "unknown"))]
+use async_std::task::spawn;
+#[cfg(target_os = "unknown")]
+use async_std::task::spawn_local as spawn;
+
+#[cfg(target_arch = "wasm32")]
+wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
+
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn drop_local() {
     static DROP_LOCAL: AtomicBool = AtomicBool::new(false);
 
@@ -20,7 +29,7 @@ fn drop_local() {
     }
 
     // Spawn a task that just touches its task-local.
-    let handle = task::spawn(async {
+    let handle = spawn(async {
         LOCAL.with(|_| ());
     });
     let task = handle.task().clone();
diff --git a/tests/tcp.rs b/tests/tcp.rs
index d92cff0..f21737e 100644
--- a/tests/tcp.rs
+++ b/tests/tcp.rs
@@ -1,3 +1,5 @@
+#![cfg(not(target_os = "unknown"))]
+
 use async_std::io;
 use async_std::net::{TcpListener, TcpStream};
 use async_std::prelude::*;
diff --git a/tests/timeout.rs b/tests/timeout.rs
index c9694f8..8ad358a 100644
--- a/tests/timeout.rs
+++ b/tests/timeout.rs
@@ -3,7 +3,11 @@ use std::time::Duration;
 use async_std::future::timeout;
 use async_std::task;
 
+#[cfg(target_arch = "wasm32")]
+wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);
+
 #[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 fn timeout_future_many() {
     task::block_on(async {
         let futures = (0..100)
diff --git a/tests/udp.rs b/tests/udp.rs
index 319dc74..15404f8 100644
--- a/tests/udp.rs
+++ b/tests/udp.rs
@@ -1,3 +1,5 @@
+#![cfg(not(target_os = "unknown"))]
+
 use async_std::io;
 use async_std::net::UdpSocket;
 use async_std::task;
diff --git a/tests/uds.rs b/tests/uds.rs
index 3ab4d6b..038ac0e 100644
--- a/tests/uds.rs
+++ b/tests/uds.rs
@@ -1,4 +1,4 @@
-#![cfg(unix)]
+#![cfg(all(unix, not(target_os = "unknown")))]
 
 use async_std::io;
 use async_std::os::unix::net::{UnixDatagram, UnixListener, UnixStream};
diff --git a/tests/verbose_errors.rs b/tests/verbose_errors.rs
index 17d4261..2876183 100644
--- a/tests/verbose_errors.rs
+++ b/tests/verbose_errors.rs
@@ -1,3 +1,5 @@
+#![cfg(not(target_os = "unknown"))]
+
 use async_std::{fs, io, net::ToSocketAddrs, task};
 
 #[test]
diff --git a/wasm-test.sh b/wasm-test.sh
new file mode 100755
index 0000000..3d8be9f
--- /dev/null
+++ b/wasm-test.sh
@@ -0,0 +1,10 @@
+#!/bin/sh
+
+wasm-pack test --chrome --headless -- --features unstable --test buf_writer
+wasm-pack test --chrome --headless -- --features unstable --test channel
+wasm-pack test --chrome --headless -- --features unstable --test condvar
+wasm-pack test --chrome --headless -- --features unstable --test mutex
+wasm-pack test --chrome --headless -- --features unstable --test rwlock
+wasm-pack test --chrome --headless -- --features unstable --test stream
+wasm-pack test --chrome --headless -- --features unstable --test task_local
+wasm-pack test --chrome --headless -- --features unstable --test timeout