diff --git a/tests/by-util/test_du.rs b/tests/by-util/test_du.rs
index c5d262c3b..e4dca7a61 100644
--- a/tests/by-util/test_du.rs
+++ b/tests/by-util/test_du.rs
@@ -187,7 +187,7 @@ fn test_du_d_flag() {
                 // TODO: gnu `du` doesn't use trailing "/" here
                 // result.stdout_str(), result_reference.stdout_str()
                 result.stdout_str().trim_end_matches("/\n"),
-                result_reference.stdout_str().trim_end_matches("\n")
+                result_reference.stdout_str().trim_end_matches('\n')
             );
             return;
         }