diff --git a/rslib/src/lib.rs b/rslib/src/lib.rs
index b55f7890e..c6fabe2e3 100644
--- a/rslib/src/lib.rs
+++ b/rslib/src/lib.rs
@@ -1,6 +1,8 @@
 // Copyright: Ankitects Pty Ltd and contributors
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
+#![deny(unused_must_use)]
+
 mod backend_proto;
 
 pub mod backend;