diff --git a/serde/src/lib.rs b/serde/src/lib.rs
index f3e44a9c..bf5548a8 100644
--- a/serde/src/lib.rs
+++ b/serde/src/lib.rs
@@ -89,7 +89,6 @@
 //
 //    https://github.com/serde-rs/serde/issues/812
 #![cfg_attr(feature = "unstable", feature(nonzero, specialization))]
-#![cfg_attr(all(feature = "std", feature = "unstable"), feature(into_boxed_c_str))]
 #![cfg_attr(feature = "alloc", feature(alloc))]
 
 // Whitelisted clippy lints.
diff --git a/test_suite/tests/test_de.rs b/test_suite/tests/test_de.rs
index b915fba7..2e062840 100644
--- a/test_suite/tests/test_de.rs
+++ b/test_suite/tests/test_de.rs
@@ -6,8 +6,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![cfg_attr(feature = "unstable", feature(into_boxed_c_str))]
-
 #[macro_use]
 extern crate serde_derive;