diff --git a/optee-utee/src/lib.rs b/optee-utee/src/lib.rs
index 1622a9ae..877a9c37 100644
--- a/optee-utee/src/lib.rs
+++ b/optee-utee/src/lib.rs
@@ -16,7 +16,6 @@
 // under the License.
 
 #![cfg_attr(not(feature = "std"), no_std)]
-#![cfg_attr(not(feature = "std"), feature(error_in_core))]
 
 // Requires `alloc`.
 #[macro_use]