diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index c0f345443b907..1211747abd80d 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -63,6 +63,7 @@
 #![warn(missing_debug_implementations)]
 #![deny(intra_doc_link_resolution_failure)] // rustdoc is run without -D warnings
 #![allow(explicit_outlives_requirements)]
+#![cfg_attr(not(bootstrap), allow(incomplete_features))]
 
 #![cfg_attr(not(test), feature(generator_trait))]
 #![cfg_attr(test, feature(test))]
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index bdfc1e66fd494..4d627383fd7cc 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -63,6 +63,7 @@
 #![warn(missing_debug_implementations)]
 #![deny(intra_doc_link_resolution_failure)] // rustdoc is run without -D warnings
 #![allow(explicit_outlives_requirements)]
+#![cfg_attr(not(bootstrap), allow(incomplete_features))]
 
 #![feature(allow_internal_unstable)]
 #![feature(arbitrary_self_types)]