diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
new file mode 100644
index 0000000..cae8cb0
--- /dev/null
+++ b/.cargo_vcs_info.json
@@ -0,0 +1,5 @@
+{
+  "git": {
+    "sha1": "f201f1457476f0829c4d7704a1cc02bef7aacb83"
+  }
+}
diff --git a/Android.bp b/Android.bp
index 5caa0f5..0c1448a 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1,4 +1,5 @@
 // This file is generated by cargo2android.py --run --dependencies --device --tests.
+// Do not modify this file as changes will be overridden on upgrade.
 
 package {
     default_applicable_licenses: [
@@ -40,27 +41,36 @@
 
 rust_library {
     name: "libpeeking_take_while",
+    // has rustc warnings
     host_supported: true,
     crate_name: "peeking_take_while",
+    cargo_env_compat: true,
+    cargo_pkg_version: "1.0.0",
     srcs: ["src/lib.rs"],
-    edition: "2015",
+    edition: "2018",
 }
 
 rust_defaults {
-    name: "peeking_take_while_defaults",
+    name: "peeking_take_while_test_defaults",
     crate_name: "peeking_take_while",
+    // has rustc warnings
     srcs: ["src/lib.rs"],
+    cargo_env_compat: true,
+    cargo_pkg_version: "1.0.0",
     test_suites: ["general-tests"],
     auto_gen_config: true,
-    edition: "2015",
+    edition: "2018",
 }
 
 rust_test_host {
     name: "peeking_take_while_host_test_src_lib",
-    defaults: ["peeking_take_while_defaults"],
+    defaults: ["peeking_take_while_test_defaults"],
+    test_options: {
+        unit_test: true,
+    },
 }
 
 rust_test {
     name: "peeking_take_while_device_test_src_lib",
-    defaults: ["peeking_take_while_defaults"],
+    defaults: ["peeking_take_while_test_defaults"],
 }
diff --git a/Cargo.toml b/Cargo.toml
index 40aeef2..f4b6efb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,14 +1,24 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
 [package]
+edition = "2018"
+name = "peeking_take_while"
+version = "1.0.0"
 authors = ["Nick Fitzgerald <fitzgen@gmail.com>"]
 description = "Like `Iterator::take_while`, but calls the predicate on a peeked value. This allows you to use `Iterator::by_ref` and `Iterator::take_while` together, and still get the first value for which the `take_while` predicate returned false after dropping the `by_ref`."
-categories = ["rust-patterns"]
-keywords = ["iterator", "take_while", "peek", "by_ref"]
-license = "Apache-2.0/MIT"
-name = "peeking_take_while"
 readme = "./README.md"
+keywords = ["iterator", "take_while", "peek", "by_ref"]
+categories = ["no-std", "rust-patterns"]
+license = "MIT OR Apache-2.0"
 repository = "https://github.com/fitzgen/peeking_take_while"
-version = "0.1.2"
-
-[badges]
 [badges.travis-ci]
 repository = "fitzgen/peeking_take_while"
diff --git a/Cargo.toml.orig b/Cargo.toml.orig
new file mode 100644
index 0000000..5075103
--- /dev/null
+++ b/Cargo.toml.orig
@@ -0,0 +1,15 @@
+[package]
+authors = ["Nick Fitzgerald <fitzgen@gmail.com>"]
+description = "Like `Iterator::take_while`, but calls the predicate on a peeked value. This allows you to use `Iterator::by_ref` and `Iterator::take_while` together, and still get the first value for which the `take_while` predicate returned false after dropping the `by_ref`."
+categories = ["no-std", "rust-patterns"]
+edition = "2018"
+keywords = ["iterator", "take_while", "peek", "by_ref"]
+license = "MIT OR Apache-2.0"
+name = "peeking_take_while"
+readme = "./README.md"
+repository = "https://github.com/fitzgen/peeking_take_while"
+version = "1.0.0"
+
+[badges]
+[badges.travis-ci]
+repository = "fitzgen/peeking_take_while"
diff --git a/METADATA b/METADATA
index 9fc8d6a..2cb4b6c 100644
--- a/METADATA
+++ b/METADATA
@@ -7,13 +7,13 @@
   }
   url {
     type: ARCHIVE
-    value: "https://static.crates.io/crates/peeking_take_while/peeking_take_while-0.1.2.crate"
+    value: "https://static.crates.io/crates/peeking_take_while/peeking_take_while-1.0.0.crate"
   }
-  version: "0.1.2"
+  version: "1.0.0"
   license_type: NOTICE
   last_upgrade_date {
-    year: 2020
-    month: 3
-    day: 31
+    year: 2021
+    month: 9
+    day: 30
   }
 }
diff --git a/README.md b/README.md
index c7486b7..988ec30 100644
--- a/README.md
+++ b/README.md
@@ -15,8 +15,6 @@
 `false`, and it will be lost.
 
 ```rust
-extern crate peeking_take_while;
-
 // Bring the `peeking_take_while` method for peekable iterators into
 // scope.
 use peeking_take_while::PeekableExt;
diff --git a/patches/std.diff b/patches/std.diff
new file mode 100644
index 0000000..3849c79
--- /dev/null
+++ b/patches/std.diff
@@ -0,0 +1,15 @@
+diff --git a/src/lib.rs b/src/lib.rs
+index 9fc1c3e..ee4c928 100644
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -67,6 +67,10 @@
+     unsafe_code
+ )]
+ 
++// ANDROID: Unconditionally use std to allow building as a dylib
++#[macro_use]
++extern crate std;
++
+ use core::fmt;
+ 
+ /// The `Iterator` extension trait that provides the `peeking_take_while`
diff --git a/src/lib.rs b/src/lib.rs
index 67f36d8..ee4c928 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,3 @@
-//! # `peeking_take_while`
-//!
 //! Provides the `peeking_take_while` iterator adaptor method.
 //!
 //! The `peeking_take_while` method is very similar to `take_while`, but behaves
@@ -12,9 +10,11 @@
 //! other hand, `take_while` will consume that first item for which the
 //! predicate returns `false`, and it will be lost.
 //!
-//! ```
-//! extern crate peeking_take_while;
+//! In case the closure may have side effects, it could be necessary to apply
+//! [`fuse`](Iterator::fuse) on the returned iterator, to prevent the predicate
+//! from being called after it first returned `false`.
 //!
+//! ```
 //! // Bring the `peeking_take_while` method for peekable iterators into
 //! // scope.
 //! use peeking_take_while::PeekableExt;
@@ -58,60 +58,166 @@
 //! # }
 //! ```
 
-use std::iter::Peekable;
+#![no_std]
+#![forbid(
+    clippy::as_conversions,
+    clippy::cast_ptr_alignment,
+    missing_docs,
+    trivial_casts,
+    unsafe_code
+)]
 
-/// The iterator returned by `peeking_take_while`.
-///
-/// See the [module documentation](./index.html) for details.
-pub struct PeekingTakeWhile<'a, I, P>
-    where I: 'a + Iterator
-{
-    iter: &'a mut Peekable<I>,
-    predicate: P,
-}
+// ANDROID: Unconditionally use std to allow building as a dylib
+#[macro_use]
+extern crate std;
 
-impl<'a, I, P> Iterator for PeekingTakeWhile<'a, I, P>
-    where I: Iterator,
-          I::Item: ::std::fmt::Debug,
-          P: FnMut(&<I as Iterator>::Item) -> bool
-{
-    type Item = <I as Iterator>::Item;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        let predicate = &mut self.predicate;
-        if self.iter.peek().map_or(false, |x| !(predicate)(x)) {
-            None
-        } else {
-            self.iter.next()
-        }
-    }
-}
+use core::fmt;
 
 /// The `Iterator` extension trait that provides the `peeking_take_while`
 /// method.
 ///
 /// See the [module documentation](./index.html) for details.
-pub trait PeekableExt<'a, I>: Iterator
-    where I: 'a + Iterator
+pub trait PeekableExt<I>: Iterator
+where
+    I: Iterator,
 {
-    /// The `Iterator` extension trait that provides the `peeking_take_while`
-    /// method.
+    /// The `peeking_take_while` method is very similar to `take_while`, but behaves
+    /// differently when used with a borrowed iterator (perhaps returned by
+    /// `Iterator::by_ref`).
     ///
-    /// See the [module documentation](./index.html) for details.
-    fn peeking_take_while<P>(&'a mut self, predicate: P) -> PeekingTakeWhile<'a, I, P>
-        where Self: Sized,
-              P: FnMut(&<Self as Iterator>::Item) -> bool;
+    /// `peeking_take_while` peeks at the next item in the iterator and runs the
+    /// predicate on that peeked item. This avoids consuming the first item yielded
+    /// by the underlying iterator for which the predicate returns `false`. On the
+    /// other hand, `take_while` will consume that first item for which the
+    /// predicate returns `false`, and it will be lost.
+    ///
+    /// In contrast to `take_while`, iterating the iterator might call the predicate again
+    /// after it first returned `false` (the returned iterator isn't fused).
+    /// If that is not intended, calling [`fuse`](Iterator::fuse) on the returned iterator
+    /// prevents that.
+    fn peeking_take_while<P>(&mut self, predicate: P) -> PeekingTakeWhile<'_, I, P>
+    where
+        P: FnMut(&Self::Item) -> bool;
 }
 
-impl<'a, I> PeekableExt<'a, I> for Peekable<I>
-    where I: 'a + Iterator
-{
-    fn peeking_take_while<P>(&'a mut self, predicate: P) -> PeekingTakeWhile<I, P>
-        where P: FnMut(&<Self as Iterator>::Item) -> bool
+impl<I: Iterator> PeekableExt<I> for core::iter::Peekable<I> {
+    #[inline]
+    fn peeking_take_while<P>(&mut self, predicate: P) -> PeekingTakeWhile<'_, I, P>
+    where
+        P: FnMut(&Self::Item) -> bool,
     {
         PeekingTakeWhile {
             iter: self,
-            predicate: predicate,
+            predicate,
         }
     }
 }
+
+/// The iterator returned by `peeking_take_while`.
+///
+/// See the [module documentation](./index.html) for details.
+pub struct PeekingTakeWhile<'a, I, P>
+where
+    I: Iterator,
+{
+    pub(crate) iter: &'a mut core::iter::Peekable<I>,
+    pub(crate) predicate: P,
+}
+
+impl<I, P> fmt::Debug for PeekingTakeWhile<'_, I, P>
+where
+    I: Iterator + fmt::Debug,
+    I::Item: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("PeekingTakeWhile")
+            .field("iter", &self.iter)
+            .finish()
+    }
+}
+
+impl<I, P> Iterator for PeekingTakeWhile<'_, I, P>
+where
+    I: Iterator,
+    P: FnMut(&I::Item) -> bool,
+{
+    type Item = I::Item;
+
+    #[inline]
+    fn next(&mut self) -> Option<Self::Item> {
+        self.iter.next_if(&mut self.predicate)
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        // can't know a lower bound, due to the predicate
+        (0, self.iter.size_hint().1)
+    }
+
+    #[inline]
+    fn fold<B, F>(mut self, mut accum: B, mut f: F) -> B
+    where
+        F: FnMut(B, I::Item) -> B,
+    {
+        while let Some(x) = self.iter.next_if(&mut self.predicate) {
+            accum = f(accum, x);
+        }
+        accum
+    }
+}
+
+// interestingly, `PeekingTakeWhile` is not automatically fused,
+// even when the inner iterator is fused, see also: `tests::not_fused`.
+
+#[cfg(test)]
+mod tests {
+    use crate::PeekableExt;
+
+    #[test]
+    fn basic() {
+        let mut it0 = (1..11).peekable();
+        let a: u32 = it0.peeking_take_while(|&i| i < 5).sum();
+        let b: u32 = it0.sum();
+        assert_eq!(a, 10);
+        assert_eq!(b, 45);
+    }
+
+    #[test]
+    fn basic_fused() {
+        let mut it0 = (1..11).peekable();
+        let a: u32 = it0.peeking_take_while(|&i| i < 5).fuse().sum();
+        let b: u32 = it0.sum();
+        assert_eq!(a, 10);
+        assert_eq!(b, 45);
+    }
+
+    #[test]
+    fn not_fused() {
+        let mut it0 = (0..10).peekable();
+        let mut ax = true;
+        let mut it1 = it0.peeking_take_while(|_| {
+            ax = !ax;
+            ax
+        });
+        assert!(it1.next().is_none());
+        assert_eq!(it1.next(), Some(0));
+        assert!(it1.next().is_none());
+        assert_eq!(it1.next(), Some(1));
+        assert_eq!(ax, true);
+    }
+
+    #[test]
+    fn fused() {
+        let mut it0 = (0..10).peekable();
+        let mut ax = true;
+        let mut it1 = it0
+            .peeking_take_while(|_| {
+                ax = !ax;
+                ax
+            })
+            .fuse();
+        assert!(it1.next().is_none());
+        assert!(it1.next().is_none());
+        assert_eq!(ax, false);
+    }
+}