diff --git a/tests/testsuite/future_incompat_report.rs b/tests/testsuite/future_incompat_report.rs
index 9f451a64c6b..4d2c66d17f3 100644
--- a/tests/testsuite/future_incompat_report.rs
+++ b/tests/testsuite/future_incompat_report.rs
@@ -164,7 +164,7 @@ fn test_multi_crate() {
                 second-dep = "*"
               "#,
         )
-        .file("src/main.rs", "fn main() {}")
+        .file("src/lib.rs", "")
         .build();
 
     for command in &["build", "check", "rustc", "test"] {