diff --git a/Cargo.toml b/Cargo.toml
index 6665f6a..0956bb5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,7 +14,8 @@ serde_test = { version = "1.0", optional = true }
 
 [features]
 default = ["std"]
-std = []
+std = ["alloc"]
+alloc = []
 
 [[test]]
 name = "tests"
diff --git a/README.md b/README.md
index 092e439..b7dc1bb 100644
--- a/README.md
+++ b/README.md
@@ -17,17 +17,20 @@ ascii = "1.0"
 
 Most of `AsciiChar` and `AsciiStr` can be used without `std` by disabling the
 default features. The owned string type `AsciiString` and the conversion trait
-`IntoAsciiString` as well as all methods referring to these types and
-`CStr` and `CString` are unavailable.
-The `Error` trait is also unavailable, but `description()` is made
-available as an inherent method for `ToAsciiCharError` and `AsAsciiStrError`.
+`IntoAsciiString` as well as all methods referring to these types can be
+re-enabled by enabling the `alloc` feature.
 
-To use the `ascii` crate in `core`-only mode in your cargo project just add the
-following dependency declaration in `Cargo.toml`:
+Methods referring to `CStr` and `CString` are also unavailable.
+The `Error` trait also only exists in `std`, but `description()` is made
+available as an inherent method for `ToAsciiCharError` and `AsAsciiStrError`
+in `#![no_std]`-mode.
+
+To use the `ascii` crate in `#![no_std]` mode in your cargo project,
+just add the following dependency declaration in `Cargo.toml`:
 
 ```toml
 [dependencies]
-ascii = { version = "1.0", default-features = false }
+ascii = { version = "1.0", default-features = false, features = ["alloc"] }
 ```
 
 ## Minimum supported Rust version
diff --git a/src/ascii_str.rs b/src/ascii_str.rs
index 836f983..e33b28f 100644
--- a/src/ascii_str.rs
+++ b/src/ascii_str.rs
@@ -1,3 +1,7 @@
+#[cfg(feature = "alloc")]
+use alloc::borrow::ToOwned;
+#[cfg(feature = "alloc")]
+use alloc::boxed::Box;
 use core::fmt;
 use core::ops::{Index, IndexMut};
 use core::ops::{Range, RangeFrom, RangeFull, RangeInclusive, RangeTo, RangeToInclusive};
@@ -8,7 +12,7 @@ use std::error::Error;
 use std::ffi::CStr;
 
 use ascii_char::AsciiChar;
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 use ascii_string::AsciiString;
 
 /// [`AsciiStr`] represents a byte or string slice that only contains ASCII characters.
@@ -77,7 +81,7 @@ impl AsciiStr {
     }
 
     /// Copies the content of this `AsciiStr` into an owned `AsciiString`.
-    #[cfg(feature = "std")]
+    #[cfg(feature = "alloc")]
     #[must_use]
     pub fn to_ascii_string(&self) -> AsciiString {
         AsciiString::from(self.slice.to_vec())
@@ -283,7 +287,7 @@ impl AsciiStr {
     }
 
     /// Returns a copy of this string where letters 'a' to 'z' are mapped to 'A' to 'Z'.
-    #[cfg(feature = "std")]
+    #[cfg(feature = "alloc")]
     #[must_use]
     pub fn to_ascii_uppercase(&self) -> AsciiString {
         let mut ascii_string = self.to_ascii_string();
@@ -292,7 +296,7 @@ impl AsciiStr {
     }
 
     /// Returns a copy of this string where letters 'A' to 'Z' are mapped to 'a' to 'z'.
-    #[cfg(feature = "std")]
+    #[cfg(feature = "alloc")]
     #[must_use]
     pub fn to_ascii_lowercase(&self) -> AsciiString {
         let mut ascii_string = self.to_ascii_string();
@@ -336,7 +340,7 @@ impl_partial_eq! {str}
 impl_partial_eq! {[u8]}
 impl_partial_eq! {[AsciiChar]}
 
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 impl ToOwned for AsciiStr {
     type Owned = AsciiString;
 
@@ -391,7 +395,7 @@ impl<'a> From<&'a mut [AsciiChar]> for &'a mut AsciiStr {
         unsafe { &mut *ptr }
     }
 }
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 impl From<Box<[AsciiChar]>> for Box<AsciiStr> {
     #[inline]
     fn from(owned: Box<[AsciiChar]>) -> Box<AsciiStr> {
@@ -451,7 +455,7 @@ impl<'a> From<&'a AsciiStr> for &'a str {
 }
 macro_rules! widen_box {
     ($wider: ty) => {
-        #[cfg(feature = "std")]
+        #[cfg(feature = "alloc")]
         impl From<Box<AsciiStr>> for Box<$wider> {
             #[inline]
             fn from(owned: Box<AsciiStr>) -> Box<$wider> {
@@ -1218,6 +1222,10 @@ impl AsAsciiStr for CStr {
 #[cfg(test)]
 mod tests {
     use super::{AsAsciiStr, AsAsciiStrError, AsMutAsciiStr, AsciiStr};
+    #[cfg(feature = "alloc")]
+    use alloc::string::{String, ToString};
+    #[cfg(feature = "alloc")]
+    use alloc::vec::Vec;
     use AsciiChar;
 
     /// Ensures that common types, `str`, `[u8]`, `AsciiStr` and their
@@ -1330,7 +1338,7 @@ mod tests {
     }
 
     #[test]
-    #[cfg(feature = "std")]
+    #[cfg(feature = "alloc")]
     fn as_mut_ascii_str() {
         macro_rules! err {{$i:expr} => {Err(AsAsciiStrError($i))}}
         let mut s: String = "abčd".to_string();
@@ -1409,7 +1417,7 @@ mod tests {
     }
 
     #[test]
-    #[cfg(feature = "std")]
+    #[cfg(feature = "alloc")]
     fn to_ascii_case() {
         let bytes = ([b'a', b'@', b'A'], [b'A', b'@', b'a']);
         let a = bytes.0.as_ascii_str().unwrap();
diff --git a/src/ascii_string.rs b/src/ascii_string.rs
index 6e0fc99..740abf0 100644
--- a/src/ascii_string.rs
+++ b/src/ascii_string.rs
@@ -1,11 +1,17 @@
-use std::any::Any;
-use std::borrow::{Borrow, BorrowMut, Cow};
+use alloc::borrow::{Borrow, BorrowMut, Cow, ToOwned};
+use alloc::fmt;
+use alloc::string::String;
+use alloc::vec::Vec;
+#[cfg(feature = "std")]
+use core::any::Any;
+use core::iter::FromIterator;
+use core::mem;
+use core::ops::{Add, AddAssign, Deref, DerefMut, Index, IndexMut};
+use core::str::FromStr;
+#[cfg(feature = "std")]
 use std::error::Error;
+#[cfg(feature = "std")]
 use std::ffi::{CStr, CString};
-use std::iter::FromIterator;
-use std::ops::{Add, AddAssign, Deref, DerefMut, Index, IndexMut};
-use std::str::FromStr;
-use std::{fmt, mem};
 
 use ascii_char::AsciiChar;
 use ascii_str::{AsAsciiStr, AsAsciiStrError, AsciiStr};
@@ -699,6 +705,7 @@ impl<O> fmt::Display for FromAsciiError<O> {
         fmt::Display::fmt(&self.error, fmtr)
     }
 }
+#[cfg(feature = "std")]
 impl<O: Any> Error for FromAsciiError<O> {
     #[inline]
     #[allow(deprecated)] // TODO: Remove deprecation once the earliest version we support deprecates this method.
@@ -799,7 +806,8 @@ impl_into_ascii_string! {String}
 impl_into_ascii_string! {'a, &'a str}
 
 /// # Notes
-/// The trailing null byte `CString` has will be removed during this conversion
+/// The trailing null byte `CString` has will be removed during this conversion.
+#[cfg(feature = "std")]
 impl IntoAsciiString for CString {
     #[inline]
     unsafe fn into_ascii_string_unchecked(self) -> AsciiString {
@@ -826,6 +834,7 @@ impl IntoAsciiString for CString {
 }
 
 /// Note that the trailing null byte will be removed in the conversion.
+#[cfg(feature = "std")]
 impl<'a> IntoAsciiString for &'a CStr {
     #[inline]
     unsafe fn into_ascii_string_unchecked(self) -> AsciiString {
@@ -885,9 +894,14 @@ where
 
 #[cfg(test)]
 mod tests {
-    use super::{AsciiString, IntoAsciiString};
+    use super::AsciiString;
+    #[cfg(feature = "std")]
+    use super::IntoAsciiString;
+    use alloc::str::FromStr;
+    use alloc::string::{String, ToString};
+    use alloc::vec::Vec;
+    #[cfg(feature = "std")]
     use std::ffi::CString;
-    use std::str::FromStr;
     use AsciiChar;
 
     #[test]
@@ -912,6 +926,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg(feature = "std")]
     fn from_cstring() {
         let cstring = CString::new("baz").unwrap();
         let ascii_str = cstring.clone().into_ascii_string().unwrap();
@@ -932,6 +947,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg(feature = "std")]
     fn fmt_ascii_string() {
         let s = "abc".to_string().into_ascii_string().unwrap();
         assert_eq!(format!("{}", s), "abc".to_string());
@@ -940,7 +956,7 @@ mod tests {
 
     #[test]
     fn write_fmt() {
-        use std::{fmt, str};
+        use alloc::{fmt, str};
 
         let mut s0 = AsciiString::new();
         fmt::write(&mut s0, format_args!("Hello World")).unwrap();
diff --git a/src/lib.rs b/src/lib.rs
index 6161c2a..a5ab819 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -54,6 +54,9 @@
 // In preparation for feature `unsafe_block_in_unsafe_fn` (https://github.com/rust-lang/rust/issues/71668)
 #![allow(unused_unsafe)]
 
+#[cfg(feature = "alloc")]
+#[cfg_attr(test, macro_use)]
+extern crate alloc;
 #[cfg(feature = "std")]
 extern crate core;
 
@@ -65,7 +68,7 @@ extern crate serde_test;
 
 mod ascii_char;
 mod ascii_str;
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 mod ascii_string;
 mod free_functions;
 #[cfg(feature = "serde")]
@@ -74,6 +77,6 @@ mod serialization;
 pub use ascii_char::{AsciiChar, ToAsciiChar, ToAsciiCharError};
 pub use ascii_str::{AsAsciiStr, AsAsciiStrError, AsMutAsciiStr, AsciiStr};
 pub use ascii_str::{Chars, CharsMut, CharsRef};
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 pub use ascii_string::{AsciiString, FromAsciiError, IntoAsciiString};
 pub use free_functions::{caret_decode, caret_encode};