diff --git a/src/lib.rs b/src/lib.rs
index a4ee3015b8d..345c22394f2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -19,11 +19,11 @@
 #![feature(
     rustc_private,
     decl_macro,
-    associated_type_bounds,
     never_type,
     trusted_len,
     hash_raw_entry
 )]
+#![cfg_attr(bootstrap, feature(associated_type_bounds))]
 #![allow(broken_intra_doc_links)]
 #![recursion_limit = "256"]
 #![warn(rust_2018_idioms)]