diff --git a/src/lib.rs b/src/lib.rs
index e62cd4d..d03b2f8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -59,7 +59,7 @@
 ))]
 
 // Attributes needed when building as part of the standard library
-#![cfg_attr(stdbuild, feature(no_std, core, core_slice_ext, staged_api))]
+#![cfg_attr(stdbuild, feature(no_std, core, core_slice_ext, staged_api, custom_attribute))]
 #![cfg_attr(stdbuild, no_std)]
 #![cfg_attr(stdbuild, staged_api)]
 #![cfg_attr(stdbuild, allow(warnings))]