diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
index 7aaf5a5fd461..b3802c1abde9 100644
--- a/library/core/src/macros/mod.rs
+++ b/library/core/src/macros/mod.rs
@@ -816,6 +816,7 @@ pub(crate) mod builtin {
     #[macro_export]
     macro_rules! env {
         ($name:expr $(,)?) => {{ /* compiler built-in */ }};
+        ($name:expr, $error_msg:expr $(,)?) => {{ /* compiler built-in */ }};
     }
 
     /// Optionally inspects an environment variable at compile time.