diff --git a/test-crates/protobuf-parse-error-test/src/lib.rs b/test-crates/protobuf-parse-error-test/src/lib.rs
index 9dc9db6c3..4a224807d 100644
--- a/test-crates/protobuf-parse-error-test/src/lib.rs
+++ b/test-crates/protobuf-parse-error-test/src/lib.rs
@@ -1,3 +1,5 @@
+#![cfg(test)]
+
 use std::fs;
 
 use protobuf_parse::Parser;