diff --git a/crates/ruff/src/test.rs b/crates/ruff/src/test.rs
index 1dcd298438..542eb168ec 100644
--- a/crates/ruff/src/test.rs
+++ b/crates/ruff/src/test.rs
@@ -1,3 +1,5 @@
+#![cfg(test)]
+
 /// Helper functions for the tests of rule implementations.
 use std::path::Path;