diff --git a/lib/cretonne/src/lib.rs b/lib/cretonne/src/lib.rs
index 9656f6d1e1..29643d552f 100644
--- a/lib/cretonne/src/lib.rs
+++ b/lib/cretonne/src/lib.rs
@@ -9,6 +9,7 @@
 #![cfg_attr(not(feature = "std"), feature(alloc))]
 
 // Include the `hashmap_core` crate if no_std
+#[allow(unused_extern_crates)]
 #[cfg(feature = "no_std")]
 extern crate hashmap_core;
 #[cfg(not(feature = "std"))]
diff --git a/lib/wasm/src/lib.rs b/lib/wasm/src/lib.rs
index 4dc802d50f..a6492b5d66 100644
--- a/lib/wasm/src/lib.rs
+++ b/lib/wasm/src/lib.rs
@@ -20,6 +20,7 @@
 #[macro_use]
 extern crate alloc;
 
+#[allow(unused_extern_crates)]
 #[cfg(feature = "no_std")]
 extern crate hashmap_core;