diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bee2562..bcda990 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -40,6 +40,7 @@ jobs:
       with:
         command:  check
         args: --features unstable --all --bins --examples --tests
+
     - name: check bench
       uses: actions-rs/cargo@v1
       if: matrix.rust == 'nightly'
@@ -71,6 +72,24 @@ jobs:
         command: test
         args: --doc --features "unstable attributes"
 
+  build__with_no_std:
+    name: Build with no-std
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@master
+
+    - name: setup
+      run: |
+        rustup default nightly
+        rustup target add thumbv7m-none-eabi
+
+    - name: check no_std
+      uses: actions-rs/cargo@v1
+      with:
+        command:  check
+        args: --no-default-features --features alloc --target thumbv7m-none-eabi -Z avoid-dev-deps
+
   check_fmt_and_docs:
     name: Checking fmt and docs
     runs-on: ubuntu-latest
diff --git a/Cargo.toml b/Cargo.toml
index 9948e8e..2d4f602 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -38,15 +38,19 @@ docs = ["attributes", "unstable", "default"]
 unstable = ["std", "broadcaster", "futures-timer"]
 attributes = ["async-attributes"]
 std = [
+  "alloc",
   "crossbeam-utils",
-  "futures-core",
+  "futures-core/std",
   "futures-io",
   "memchr",
   "once_cell",
-  "pin-project-lite",
   "pin-utils",
   "slab",
 ]
+alloc = [
+  "futures-core/alloc",
+  "pin-project-lite",
+]
 
 [dependencies]
 async-attributes = { version = "1.1.1", optional = true }
@@ -55,7 +59,7 @@ broadcaster = { version = "1.0.0", optional = true }
 crossbeam-channel = { version = "0.4.0", optional = true }
 crossbeam-deque = { version = "0.7.2", optional = true }
 crossbeam-utils = { version = "0.7.0", optional = true }
-futures-core = { version = "0.3.1", optional = true }
+futures-core = { version = "0.3.1", optional = true, default-features = false }
 futures-io = { version = "0.3.1", optional = true }
 futures-timer = { version = "2.0.2", optional = true }
 kv-log-macro = { version = "1.0.4", optional = true }
diff --git a/src/future/future/mod.rs b/src/future/future/mod.rs
index d610096..24f3fb5 100644
--- a/src/future/future/mod.rs
+++ b/src/future/future/mod.rs
@@ -21,8 +21,8 @@ cfg_unstable_default! {
 }
 
 extension_trait! {
-    use std::pin::Pin;
-    use std::ops::{Deref, DerefMut};
+    use core::pin::Pin;
+    use core::ops::{Deref, DerefMut};
 
     use crate::task::{Context, Poll};
 
@@ -136,7 +136,7 @@ extension_trait! {
 
         [`Future`]: ../future/trait.Future.html
     "#]
-    pub trait FutureExt: std::future::Future {
+    pub trait FutureExt: core::future::Future {
         /// Returns a Future that delays execution for a specified time.
         ///
         /// # Examples
diff --git a/src/future/mod.rs b/src/future/mod.rs
index 9936276..9b75533 100644
--- a/src/future/mod.rs
+++ b/src/future/mod.rs
@@ -46,15 +46,20 @@
 //! [`Future::race`]: trait.Future.html#method.race
 //! [`Future::try_race`]: trait.Future.html#method.try_race
 
-pub use future::Future;
-pub use pending::pending;
-pub use poll_fn::poll_fn;
-pub use ready::ready;
+cfg_alloc! {
+    pub use future::Future;
+    pub(crate) mod future;
+}
+
+cfg_std! {
+    pub use pending::pending;
+    pub use poll_fn::poll_fn;
+    pub use ready::ready;
 
-pub(crate) mod future;
-mod pending;
-mod poll_fn;
-mod ready;
+    mod pending;
+    mod poll_fn;
+    mod ready;
+}
 
 cfg_default! {
     pub use timeout::{timeout, TimeoutError};
diff --git a/src/lib.rs b/src/lib.rs
index c9d1277..05073a2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -221,6 +221,7 @@
 //! features = ["std"]
 //! ```
 
+#![cfg_attr(not(feature = "std"), no_std)]
 #![cfg_attr(feature = "docs", feature(doc_cfg))]
 #![warn(missing_docs, missing_debug_implementations, rust_2018_idioms)]
 #![allow(clippy::mutex_atomic, clippy::module_inception)]
@@ -229,6 +230,8 @@
 #![doc(html_logo_url = "https://async.rs/images/logo--hero.svg")]
 #![recursion_limit = "2048"]
 
+extern crate alloc;
+
 #[macro_use]
 mod utils;
 
@@ -240,14 +243,17 @@ pub use async_attributes::{main, test};
 #[cfg(feature = "std")]
 mod macros;
 
-cfg_std! {
+cfg_alloc! {
+    pub mod task;
     pub mod future;
+    pub mod stream;
+}
+
+cfg_std! {
     pub mod io;
     pub mod os;
     pub mod prelude;
-    pub mod stream;
     pub mod sync;
-    pub mod task;
 }
 
 cfg_default! {
diff --git a/src/stream/double_ended_stream/next_back.rs b/src/stream/double_ended_stream/next_back.rs
index aa642d0..9fb52b7 100644
--- a/src/stream/double_ended_stream/next_back.rs
+++ b/src/stream/double_ended_stream/next_back.rs
@@ -1,5 +1,5 @@
-use std::pin::Pin;
-use std::future::Future;
+use core::pin::Pin;
+use core::future::Future;
 
 use crate::stream::DoubleEndedStream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/double_ended_stream/nth_back.rs b/src/stream/double_ended_stream/nth_back.rs
index e32a28f..2701e9b 100644
--- a/src/stream/double_ended_stream/nth_back.rs
+++ b/src/stream/double_ended_stream/nth_back.rs
@@ -1,6 +1,6 @@
-use std::future::Future;
-use std::pin::Pin;
-use std::task::{Context, Poll};
+use core::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll};
 
 use crate::stream::DoubleEndedStream;
 
diff --git a/src/stream/double_ended_stream/rfind.rs b/src/stream/double_ended_stream/rfind.rs
index 9472693..3666551 100644
--- a/src/stream/double_ended_stream/rfind.rs
+++ b/src/stream/double_ended_stream/rfind.rs
@@ -1,6 +1,6 @@
-use std::task::{Context, Poll};
-use std::future::Future;
-use std::pin::Pin;
+use core::task::{Context, Poll};
+use core::future::Future;
+use core::pin::Pin;
 
 use crate::stream::DoubleEndedStream;
 
diff --git a/src/stream/double_ended_stream/rfold.rs b/src/stream/double_ended_stream/rfold.rs
index 9002f8d..9bc1878 100644
--- a/src/stream/double_ended_stream/rfold.rs
+++ b/src/stream/double_ended_stream/rfold.rs
@@ -1,6 +1,6 @@
-use std::future::Future;
-use std::pin::Pin;
-use std::task::{Context, Poll};
+use core::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll};
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/double_ended_stream/try_rfold.rs b/src/stream/double_ended_stream/try_rfold.rs
index 9e6295a..d67b6ec 100644
--- a/src/stream/double_ended_stream/try_rfold.rs
+++ b/src/stream/double_ended_stream/try_rfold.rs
@@ -1,5 +1,5 @@
 use crate::future::Future;
-use std::pin::Pin;
+use core::pin::Pin;
 use crate::task::{Context, Poll};
 
 use pin_project_lite::pin_project;
diff --git a/src/stream/empty.rs b/src/stream/empty.rs
index 4909070..a11337a 100644
--- a/src/stream/empty.rs
+++ b/src/stream/empty.rs
@@ -1,5 +1,5 @@
-use std::marker::PhantomData;
-use std::pin::Pin;
+use core::marker::PhantomData;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/extend.rs b/src/stream/extend.rs
index c48fe1e..702cbca 100644
--- a/src/stream/extend.rs
+++ b/src/stream/extend.rs
@@ -1,6 +1,6 @@
-use std::pin::Pin;
+use core::pin::Pin;
+use core::future::Future;
 
-use crate::prelude::*;
 use crate::stream::IntoStream;
 
 /// Extends a collection with the contents of a stream.
diff --git a/src/stream/from_fn.rs b/src/stream/from_fn.rs
index 8067176..d373645 100644
--- a/src/stream/from_fn.rs
+++ b/src/stream/from_fn.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/from_iter.rs b/src/stream/from_iter.rs
index 705d150..ea2ed8e 100644
--- a/src/stream/from_iter.rs
+++ b/src/stream/from_iter.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/from_stream.rs b/src/stream/from_stream.rs
index 67b9b3d..12d89e8 100644
--- a/src/stream/from_stream.rs
+++ b/src/stream/from_stream.rs
@@ -1,5 +1,5 @@
-use std::future::Future;
-use std::pin::Pin;
+use core::future::Future;
+use core::pin::Pin;
 
 use crate::stream::IntoStream;
 
diff --git a/src/stream/interval.rs b/src/stream/interval.rs
index f8a6ef6..7a0c174 100644
--- a/src/stream/interval.rs
+++ b/src/stream/interval.rs
@@ -2,10 +2,10 @@ use std::pin::Pin;
 use std::task::{Context, Poll};
 use std::time::{Duration, Instant};
 
+use crate::future::Future;
+use crate::stream::Stream;
 use futures_timer::Delay;
 
-use crate::prelude::*;
-
 /// Creates a new stream that yields at a set interval.
 ///
 /// The stream first yields after `dur`, and continues to yield every
diff --git a/src/stream/once.rs b/src/stream/once.rs
index 939722d..b86f181 100644
--- a/src/stream/once.rs
+++ b/src/stream/once.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/pending.rs b/src/stream/pending.rs
index 922a540..edb6be4 100644
--- a/src/stream/pending.rs
+++ b/src/stream/pending.rs
@@ -1,6 +1,6 @@
-use std::marker::PhantomData;
-use std::pin::Pin;
-use std::task::{Context, Poll};
+use core::marker::PhantomData;
+use core::pin::Pin;
+use core::task::{Context, Poll};
 
 use crate::stream::{DoubleEndedStream, ExactSizeStream, FusedStream, Stream};
 
diff --git a/src/stream/product.rs b/src/stream/product.rs
index 2f5bf4c..15497e8 100644
--- a/src/stream/product.rs
+++ b/src/stream/product.rs
@@ -1,5 +1,5 @@
-use std::pin::Pin;
-use std::future::Future;
+use core::pin::Pin;
+use core::future::Future;
 
 use crate::stream::Stream;
 
diff --git a/src/stream/repeat.rs b/src/stream/repeat.rs
index f3dfdbd..e73a2f8 100644
--- a/src/stream/repeat.rs
+++ b/src/stream/repeat.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/repeat_with.rs b/src/stream/repeat_with.rs
index e183a77..39984a3 100644
--- a/src/stream/repeat_with.rs
+++ b/src/stream/repeat_with.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/stream/all.rs b/src/stream/stream/all.rs
index d2ac5ca..06f4d7f 100644
--- a/src/stream/stream/all.rs
+++ b/src/stream/stream/all.rs
@@ -1,6 +1,6 @@
-use std::marker::PhantomData;
-use std::pin::Pin;
-use std::future::Future;
+use core::marker::PhantomData;
+use core::pin::Pin;
+use core::future::Future;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/stream/any.rs b/src/stream/stream/any.rs
index 34168e6..15154c5 100644
--- a/src/stream/stream/any.rs
+++ b/src/stream/stream/any.rs
@@ -1,6 +1,6 @@
-use std::marker::PhantomData;
-use std::pin::Pin;
-use std::future::Future;
+use core::marker::PhantomData;
+use core::pin::Pin;
+use core::future::Future;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/stream/chain.rs b/src/stream/stream/chain.rs
index 909fc19..c034a53 100644
--- a/src/stream/stream/chain.rs
+++ b/src/stream/stream/chain.rs
@@ -1,9 +1,10 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::fuse::Fuse;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
+use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
 pin_project! {
diff --git a/src/stream/stream/cloned.rs b/src/stream/stream/cloned.rs
index 4c77c5c..eac992d 100644
--- a/src/stream/stream/cloned.rs
+++ b/src/stream/stream/cloned.rs
@@ -1,7 +1,7 @@
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 use pin_project_lite::pin_project;
-use std::pin::Pin;
+use core::pin::Pin;
 
 pin_project! {
     /// A stream that clones the elements of an underlying stream.
diff --git a/src/stream/stream/cmp.rs b/src/stream/stream/cmp.rs
index 2be0c1a..9d2b0ec 100644
--- a/src/stream/stream/cmp.rs
+++ b/src/stream/stream/cmp.rs
@@ -1,11 +1,11 @@
-use std::cmp::Ordering;
-use std::pin::Pin;
-use std::future::Future;
+use core::cmp::Ordering;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::fuse::Fuse;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
diff --git a/src/stream/stream/copied.rs b/src/stream/stream/copied.rs
index 651c31b..19296f5 100644
--- a/src/stream/stream/copied.rs
+++ b/src/stream/stream/copied.rs
@@ -1,7 +1,7 @@
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 use pin_project_lite::pin_project;
-use std::pin::Pin;
+use core::pin::Pin;
 
 pin_project! {
     /// A stream that copies the elements of an underlying stream.
diff --git a/src/stream/stream/count.rs b/src/stream/stream/count.rs
index 1ca8aef..63e0449 100644
--- a/src/stream/stream/count.rs
+++ b/src/stream/stream/count.rs
@@ -1,5 +1,5 @@
-use std::future::Future;
-use std::pin::Pin;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/cycle.rs b/src/stream/stream/cycle.rs
index 5f8eaa2..ef46d1a 100644
--- a/src/stream/stream/cycle.rs
+++ b/src/stream/stream/cycle.rs
@@ -1,5 +1,5 @@
-use std::mem::ManuallyDrop;
-use std::pin::Pin;
+use core::mem::ManuallyDrop;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/stream/delay.rs b/src/stream/stream/delay.rs
index 5768792..ff4c937 100644
--- a/src/stream/stream/delay.rs
+++ b/src/stream/stream/delay.rs
@@ -1,6 +1,6 @@
-use std::future::Future;
-use std::pin::Pin;
-use std::time::Duration;
+use core::future::Future;
+use core::pin::Pin;
+use core::time::Duration;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/enumerate.rs b/src/stream/stream/enumerate.rs
index c4a37d6..093fefb 100644
--- a/src/stream/stream/enumerate.rs
+++ b/src/stream/stream/enumerate.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/eq.rs b/src/stream/stream/eq.rs
index 58ccc90..3d8307b 100644
--- a/src/stream/stream/eq.rs
+++ b/src/stream/stream/eq.rs
@@ -1,10 +1,10 @@
-use std::pin::Pin;
-use std::future::Future;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::fuse::Fuse;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
diff --git a/src/stream/stream/filter.rs b/src/stream/stream/filter.rs
index 00344b0..2dc7dd4 100644
--- a/src/stream/stream/filter.rs
+++ b/src/stream/stream/filter.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/filter_map.rs b/src/stream/stream/filter_map.rs
index 3cd1e47..e43e8f0 100644
--- a/src/stream/stream/filter_map.rs
+++ b/src/stream/stream/filter_map.rs
@@ -1,5 +1,5 @@
-use std::pin::Pin;
-use std::task::{Context, Poll};
+use core::pin::Pin;
+use core::task::{Context, Poll};
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/find.rs b/src/stream/stream/find.rs
index 4a0749b..8652ac0 100644
--- a/src/stream/stream/find.rs
+++ b/src/stream/stream/find.rs
@@ -1,5 +1,5 @@
-use std::future::Future;
-use std::pin::Pin;
+use core::future::Future;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/stream/find_map.rs b/src/stream/stream/find_map.rs
index c794943..f7e3c1e 100644
--- a/src/stream/stream/find_map.rs
+++ b/src/stream/stream/find_map.rs
@@ -1,6 +1,6 @@
-use std::future::Future;
-use std::pin::Pin;
-use std::task::{Context, Poll};
+use core::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll};
 
 use crate::stream::Stream;
 
diff --git a/src/stream/stream/flat_map.rs b/src/stream/stream/flat_map.rs
index 9a7d921..e07893a 100644
--- a/src/stream/stream/flat_map.rs
+++ b/src/stream/stream/flat_map.rs
@@ -1,9 +1,9 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
-use crate::prelude::*;
 use crate::stream::stream::map::Map;
+use crate::stream::stream::StreamExt;
 use crate::stream::{IntoStream, Stream};
 use crate::task::{Context, Poll};
 
diff --git a/src/stream/stream/flatten.rs b/src/stream/stream/flatten.rs
index 1d6fcae..f2e275c 100644
--- a/src/stream/stream/flatten.rs
+++ b/src/stream/stream/flatten.rs
@@ -1,5 +1,5 @@
-use std::fmt;
-use std::pin::Pin;
+use core::fmt;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/fold.rs b/src/stream/stream/fold.rs
index a346eb6..3938a37 100644
--- a/src/stream/stream/fold.rs
+++ b/src/stream/stream/fold.rs
@@ -1,5 +1,5 @@
-use std::future::Future;
-use std::pin::Pin;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/for_each.rs b/src/stream/stream/for_each.rs
index dce5cda..dbada10 100644
--- a/src/stream/stream/for_each.rs
+++ b/src/stream/stream/for_each.rs
@@ -1,5 +1,5 @@
-use std::pin::Pin;
-use std::future::Future;
+use core::pin::Pin;
+use core::future::Future;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/fuse.rs b/src/stream/stream/fuse.rs
index c7449c2..f3a0596 100644
--- a/src/stream/stream/fuse.rs
+++ b/src/stream/stream/fuse.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/ge.rs b/src/stream/stream/ge.rs
index 67b20be..1e1b70d 100644
--- a/src/stream/stream/ge.rs
+++ b/src/stream/stream/ge.rs
@@ -1,11 +1,11 @@
-use std::cmp::Ordering;
-use std::pin::Pin;
-use std::future::Future;
+use core::cmp::Ordering;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::partial_cmp::PartialCmpFuture;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
diff --git a/src/stream/stream/gt.rs b/src/stream/stream/gt.rs
index 1c12189..d58e7e9 100644
--- a/src/stream/stream/gt.rs
+++ b/src/stream/stream/gt.rs
@@ -1,11 +1,11 @@
-use std::cmp::Ordering;
-use std::pin::Pin;
-use std::future::Future;
+use core::cmp::Ordering;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::partial_cmp::PartialCmpFuture;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
diff --git a/src/stream/stream/inspect.rs b/src/stream/stream/inspect.rs
index bb39662..481810d 100644
--- a/src/stream/stream/inspect.rs
+++ b/src/stream/stream/inspect.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/last.rs b/src/stream/stream/last.rs
index d037efc..ebf1a48 100644
--- a/src/stream/stream/last.rs
+++ b/src/stream/stream/last.rs
@@ -1,5 +1,5 @@
-use std::future::Future;
-use std::pin::Pin;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/le.rs b/src/stream/stream/le.rs
index 7b86161..169f9ec 100644
--- a/src/stream/stream/le.rs
+++ b/src/stream/stream/le.rs
@@ -1,11 +1,11 @@
-use std::cmp::Ordering;
-use std::pin::Pin;
-use std::future::Future;
+use core::cmp::Ordering;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::partial_cmp::PartialCmpFuture;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
diff --git a/src/stream/stream/lt.rs b/src/stream/stream/lt.rs
index 100a003..1851b8e 100644
--- a/src/stream/stream/lt.rs
+++ b/src/stream/stream/lt.rs
@@ -1,11 +1,11 @@
-use std::cmp::Ordering;
-use std::pin::Pin;
-use std::future::Future;
+use core::cmp::Ordering;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::partial_cmp::PartialCmpFuture;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
diff --git a/src/stream/stream/map.rs b/src/stream/stream/map.rs
index 8e074a7..0eab3ce 100644
--- a/src/stream/stream/map.rs
+++ b/src/stream/stream/map.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/max.rs b/src/stream/stream/max.rs
index d8ff119..8a4d594 100644
--- a/src/stream/stream/max.rs
+++ b/src/stream/stream/max.rs
@@ -1,7 +1,7 @@
-use std::cmp::{Ord, Ordering};
-use std::marker::PhantomData;
-use std::pin::Pin;
-use std::future::Future;
+use core::cmp::{Ord, Ordering};
+use core::marker::PhantomData;
+use core::pin::Pin;
+use core::future::Future;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/max_by.rs b/src/stream/stream/max_by.rs
index 36b876b..8f98645 100644
--- a/src/stream/stream/max_by.rs
+++ b/src/stream/stream/max_by.rs
@@ -1,6 +1,6 @@
-use std::cmp::Ordering;
-use std::pin::Pin;
-use std::future::Future;
+use core::cmp::Ordering;
+use core::pin::Pin;
+use core::future::Future;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/max_by_key.rs b/src/stream/stream/max_by_key.rs
index e421f94..8fa91ab 100644
--- a/src/stream/stream/max_by_key.rs
+++ b/src/stream/stream/max_by_key.rs
@@ -1,6 +1,6 @@
-use std::cmp::Ordering;
-use std::future::Future;
-use std::pin::Pin;
+use core::cmp::Ordering;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/merge.rs b/src/stream/stream/merge.rs
index 84ac432..2320972 100644
--- a/src/stream/stream/merge.rs
+++ b/src/stream/stream/merge.rs
@@ -1,10 +1,11 @@
-use std::pin::Pin;
-use std::task::{Context, Poll};
+use core::pin::Pin;
+use core::task::{Context, Poll};
 
 use pin_project_lite::pin_project;
 
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
 use crate::stream::Fuse;
+use crate::stream::Stream;
 use crate::utils;
 
 pin_project! {
diff --git a/src/stream/stream/min.rs b/src/stream/stream/min.rs
index 4ce52be..4fe2a67 100644
--- a/src/stream/stream/min.rs
+++ b/src/stream/stream/min.rs
@@ -1,7 +1,7 @@
-use std::cmp::{Ord, Ordering};
-use std::marker::PhantomData;
-use std::pin::Pin;
-use std::future::Future;
+use core::cmp::{Ord, Ordering};
+use core::marker::PhantomData;
+use core::pin::Pin;
+use core::future::Future;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/min_by.rs b/src/stream/stream/min_by.rs
index e35719e..fe1d40e 100644
--- a/src/stream/stream/min_by.rs
+++ b/src/stream/stream/min_by.rs
@@ -1,6 +1,6 @@
-use std::cmp::Ordering;
-use std::pin::Pin;
-use std::future::Future;
+use core::cmp::Ordering;
+use core::pin::Pin;
+use core::future::Future;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/min_by_key.rs b/src/stream/stream/min_by_key.rs
index 07c3642..549b798 100644
--- a/src/stream/stream/min_by_key.rs
+++ b/src/stream/stream/min_by_key.rs
@@ -1,6 +1,6 @@
-use std::cmp::Ordering;
-use std::future::Future;
-use std::pin::Pin;
+use core::cmp::Ordering;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/mod.rs b/src/stream/stream/mod.rs
index 6c84ac2..d0cc718 100644
--- a/src/stream/stream/mod.rs
+++ b/src/stream/stream/mod.rs
@@ -110,12 +110,12 @@ pub use take::Take;
 pub use take_while::TakeWhile;
 pub use zip::Zip;
 
-use std::cmp::Ordering;
+use core::cmp::Ordering;
 
 cfg_unstable! {
-    use std::future::Future;
-    use std::pin::Pin;
-    use std::time::Duration;
+    use core::future::Future;
+    use core::pin::Pin;
+    use core::time::Duration;
 
     use crate::stream::into_stream::IntoStream;
     use crate::stream::{FromStream, Product, Sum};
diff --git a/src/stream/stream/ne.rs b/src/stream/stream/ne.rs
index ec11d1f..c51ab31 100644
--- a/src/stream/stream/ne.rs
+++ b/src/stream/stream/ne.rs
@@ -1,10 +1,10 @@
-use std::pin::Pin;
-use std::future::Future;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::fuse::Fuse;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
diff --git a/src/stream/stream/next.rs b/src/stream/stream/next.rs
index 23abb0b..7bd2083 100644
--- a/src/stream/stream/next.rs
+++ b/src/stream/stream/next.rs
@@ -1,5 +1,5 @@
-use std::pin::Pin;
-use std::future::Future;
+use core::pin::Pin;
+use core::future::Future;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/stream/nth.rs b/src/stream/stream/nth.rs
index 267bd40..8cdabb6 100644
--- a/src/stream/stream/nth.rs
+++ b/src/stream/stream/nth.rs
@@ -1,6 +1,6 @@
-use std::pin::Pin;
-use std::task::{Context, Poll};
-use std::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll};
+use core::future::Future;
 
 use crate::stream::Stream;
 
diff --git a/src/stream/stream/partial_cmp.rs b/src/stream/stream/partial_cmp.rs
index 85587c9..928a03b 100644
--- a/src/stream/stream/partial_cmp.rs
+++ b/src/stream/stream/partial_cmp.rs
@@ -1,11 +1,11 @@
-use std::cmp::Ordering;
-use std::future::Future;
-use std::pin::Pin;
+use core::cmp::Ordering;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::fuse::Fuse;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
diff --git a/src/stream/stream/partition.rs b/src/stream/stream/partition.rs
index aaf58ac..69268ec 100644
--- a/src/stream/stream/partition.rs
+++ b/src/stream/stream/partition.rs
@@ -1,7 +1,7 @@
 use pin_project_lite::pin_project;
-use std::default::Default;
-use std::future::Future;
-use std::pin::Pin;
+use core::default::Default;
+use core::future::Future;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/stream/position.rs b/src/stream/stream/position.rs
index df60eaa..2811b6d 100644
--- a/src/stream/stream/position.rs
+++ b/src/stream/stream/position.rs
@@ -1,5 +1,5 @@
-use std::future::Future;
-use std::pin::Pin;
+use core::future::Future;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/stream/scan.rs b/src/stream/stream/scan.rs
index 385edf8..d72b0dc 100644
--- a/src/stream/stream/scan.rs
+++ b/src/stream/stream/scan.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/skip.rs b/src/stream/stream/skip.rs
index bcff50d..52b137d 100644
--- a/src/stream/stream/skip.rs
+++ b/src/stream/stream/skip.rs
@@ -1,5 +1,5 @@
-use std::pin::Pin;
-use std::task::{Context, Poll};
+use core::pin::Pin;
+use core::task::{Context, Poll};
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/skip_while.rs b/src/stream/stream/skip_while.rs
index 2334713..d139de4 100644
--- a/src/stream/stream/skip_while.rs
+++ b/src/stream/stream/skip_while.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/step_by.rs b/src/stream/stream/step_by.rs
index 2149cda..3dd3d62 100644
--- a/src/stream/stream/step_by.rs
+++ b/src/stream/stream/step_by.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/take.rs b/src/stream/stream/take.rs
index 8c85227..ffc3e99 100644
--- a/src/stream/stream/take.rs
+++ b/src/stream/stream/take.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/take_while.rs b/src/stream/stream/take_while.rs
index 2ba8490..60eb8c5 100644
--- a/src/stream/stream/take_while.rs
+++ b/src/stream/stream/take_while.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/timeout.rs b/src/stream/stream/timeout.rs
index f580360..ce658c8 100644
--- a/src/stream/stream/timeout.rs
+++ b/src/stream/stream/timeout.rs
@@ -1,8 +1,8 @@
 use std::error::Error;
 use std::fmt;
+use std::future::Future;
 use std::pin::Pin;
 use std::time::Duration;
-use std::future::Future;
 
 use futures_timer::Delay;
 use pin_project_lite::pin_project;
diff --git a/src/stream/stream/try_fold.rs b/src/stream/stream/try_fold.rs
index 3b92d95..73312ff 100644
--- a/src/stream/stream/try_fold.rs
+++ b/src/stream/stream/try_fold.rs
@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use crate::future::Future;
 use crate::stream::Stream;
diff --git a/src/stream/stream/try_for_each.rs b/src/stream/stream/try_for_each.rs
index 86f1674..917bfd1 100644
--- a/src/stream/stream/try_for_each.rs
+++ b/src/stream/stream/try_for_each.rs
@@ -1,5 +1,5 @@
-use std::future::Future;
-use std::pin::Pin;
+use core::future::Future;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/stream/unzip.rs b/src/stream/stream/unzip.rs
index cb57578..7771509 100644
--- a/src/stream/stream/unzip.rs
+++ b/src/stream/stream/unzip.rs
@@ -1,5 +1,5 @@
-use std::future::Future;
-use std::pin::Pin;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/stream/zip.rs b/src/stream/stream/zip.rs
index 597691b..83d613c 100644
--- a/src/stream/stream/zip.rs
+++ b/src/stream/stream/zip.rs
@@ -1,5 +1,5 @@
-use std::fmt;
-use std::pin::Pin;
+use core::fmt;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
diff --git a/src/stream/successors.rs b/src/stream/successors.rs
index 4421564..a9ce40f 100644
--- a/src/stream/successors.rs
+++ b/src/stream/successors.rs
@@ -1,5 +1,5 @@
-use std::mem;
-use std::pin::Pin;
+use core::mem;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
diff --git a/src/stream/sum.rs b/src/stream/sum.rs
index 9607baf..3b3144e 100644
--- a/src/stream/sum.rs
+++ b/src/stream/sum.rs
@@ -1,5 +1,5 @@
-use std::future::Future;
-use std::pin::Pin;
+use core::future::Future;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 
diff --git a/src/task/mod.rs b/src/task/mod.rs
index f738fca..13fe903 100644
--- a/src/task/mod.rs
+++ b/src/task/mod.rs
@@ -117,13 +117,16 @@
 //! [`task_local!`]: ../macro.task_local.html
 //! [`with`]: struct.LocalKey.html#method.with
 
-cfg_std! {
+cfg_alloc! {
     #[doc(inline)]
-    pub use std::task::{Context, Poll, Waker};
-
+    pub use core::task::{Context, Poll, Waker};
     pub use ready::ready;
-    pub use yield_now::yield_now;
+
     mod ready;
+}
+
+cfg_std! {
+    pub use yield_now::yield_now;
     mod yield_now;
 }
 
diff --git a/src/utils.rs b/src/utils.rs
index ef50ed0..f18b74d 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -1,3 +1,5 @@
+use alloc::string::String;
+
 /// Calls a function and aborts if it panics.
 ///
 /// This is useful in unsafe code where we can't recover from panics.
@@ -104,6 +106,7 @@ macro_rules! cfg_unstable_default {
 
 /// Declares Unix-specific items.
 #[doc(hidden)]
+#[allow(unused_macros)]
 macro_rules! cfg_unix {
     ($($item:item)*) => {
         $(
@@ -116,6 +119,7 @@ macro_rules! cfg_unix {
 
 /// Declares Windows-specific items.
 #[doc(hidden)]
+#[allow(unused_macros)]
 macro_rules! cfg_windows {
     ($($item:item)*) => {
         $(
@@ -128,6 +132,7 @@ macro_rules! cfg_windows {
 
 /// Declares items when the "docs" feature is enabled.
 #[doc(hidden)]
+#[allow(unused_macros)]
 macro_rules! cfg_docs {
     ($($item:item)*) => {
         $(
@@ -139,6 +144,7 @@ macro_rules! cfg_docs {
 
 /// Declares items when the "docs" feature is disabled.
 #[doc(hidden)]
+#[allow(unused_macros)]
 macro_rules! cfg_not_docs {
     ($($item:item)*) => {
         $(
@@ -160,6 +166,18 @@ macro_rules! cfg_std {
     }
 }
 
+/// Declares no-std items.
+#[allow(unused_macros)]
+#[doc(hidden)]
+macro_rules! cfg_alloc {
+    ($($item:item)*) => {
+        $(
+            #[cfg(feature = "alloc")]
+            $item
+        )*
+    }
+}
+
 /// Declares default items.
 #[allow(unused_macros)]
 #[doc(hidden)]
@@ -180,6 +198,7 @@ macro_rules! cfg_default {
 ///
 /// Inside invocations of this macro, we write a definitions that looks similar to the final
 /// rendered docs, and the macro then generates all the boilerplate for us.
+#[allow(unused_macros)]
 #[doc(hidden)]
 macro_rules! extension_trait {
     (
@@ -204,14 +223,14 @@ macro_rules! extension_trait {
         #[allow(dead_code)]
         mod owned {
             #[doc(hidden)]
-            pub struct ImplFuture<T>(std::marker::PhantomData<T>);
+            pub struct ImplFuture<T>(core::marker::PhantomData<T>);
         }
 
         // A fake `impl Future` type that borrows its environment.
         #[allow(dead_code)]
         mod borrowed {
             #[doc(hidden)]
-            pub struct ImplFuture<'a, T>(std::marker::PhantomData<&'a T>);
+            pub struct ImplFuture<'a, T>(core::marker::PhantomData<&'a T>);
         }
 
         // Render a fake trait combining the bodies of the base trait and the extension trait.