diff --git a/ouroboros/Cargo.toml b/ouroboros/Cargo.toml
index 943fc24..60377da 100644
--- a/ouroboros/Cargo.toml
+++ b/ouroboros/Cargo.toml
@@ -12,3 +12,7 @@ repository = "https://github.com/joshua-maros/ouroboros"
 [dependencies]
 aliasable = "0.1.3"
 ouroboros_macro = { version = "0.15.1", path = "../ouroboros_macro" }
+
+[features]
+default = ["std"]
+std = ["ouroboros_macro/std"]
diff --git a/ouroboros/src/lib.rs b/ouroboros/src/lib.rs
index 87e50ac..a50251f 100644
--- a/ouroboros/src/lib.rs
+++ b/ouroboros/src/lib.rs
@@ -365,8 +365,11 @@ pub mod macro_help {
     }
 
     std_type_check!(is_std_box_type T alloc::boxed::Box<T>);
+    #[cfg(not(feature = "std"))]
     #[cfg(target_has_atomic = "ptr")] // alloc::sync is missing if this is false
     std_type_check!(is_std_arc_type T alloc::sync::Arc<T>);
+    #[cfg(feature = "std")]
+    std_type_check!(is_std_arc_type T alloc::sync::Arc<T>);
     std_type_check!(is_std_rc_type T alloc::rc::Rc<T>);
 
     pub fn aliasable_boxed<T>(data: T) -> AliasableBox<T> {
diff --git a/ouroboros_macro/Cargo.toml b/ouroboros_macro/Cargo.toml
index c686425..c4701f3 100644
--- a/ouroboros_macro/Cargo.toml
+++ b/ouroboros_macro/Cargo.toml
@@ -17,3 +17,6 @@ proc-macro2 = "1.0"
 proc-macro-error = "1.0.4"
 quote = "1.0"
 syn = { version = "1.0", features = ["full"] }
+
+[features]
+std = []
diff --git a/ouroboros_macro/src/covariance_detection.rs b/ouroboros_macro/src/covariance_detection.rs
index 2f50983..8c38f4b 100644
--- a/ouroboros_macro/src/covariance_detection.rs
+++ b/ouroboros_macro/src/covariance_detection.rs
@@ -3,7 +3,10 @@ use syn::{GenericArgument, PathArguments, Type};
 
 use crate::utils::uses_this_lifetime;
 
+#[cfg(feature = "std")]
 const STD_CONTAINER_TYPES: &[&str] = &["Box", "Arc", "Rc"];
+#[cfg(not(feature = "std"))]
+const STD_CONTAINER_TYPES: &[&str] = &["Box", "Rc"];
 
 /// Returns Some((type_name, element_type)) if the provided type appears to be Box, Arc, or Rc from
 /// the standard library. Returns None if not.
diff --git a/ouroboros_macro/src/generate/type_asserts.rs b/ouroboros_macro/src/generate/type_asserts.rs
index 3c8c7d1..c66d1f4 100644
--- a/ouroboros_macro/src/generate/type_asserts.rs
+++ b/ouroboros_macro/src/generate/type_asserts.rs
@@ -19,6 +19,7 @@ pub fn make_type_asserts(info: &StructInfo) -> TokenStream {
         if let Some((std_type, _eltype)) = apparent_std_container_type(field_type) {
             let checker_name = match std_type {
                 "Box" => "is_std_box_type",
+                #[cfg(feature = "std")]
                 "Arc" => "is_std_arc_type",
                 "Rc" => "is_std_rc_type",
                 _ => unreachable!(),