diff --git a/src/test/run-pass/unboxed-closures-unique-type-id.rs b/src/test/run-pass/unboxed-closures-unique-type-id.rs
index f35daa65a43..43ab16c106f 100644
--- a/src/test/run-pass/unboxed-closures-unique-type-id.rs
+++ b/src/test/run-pass/unboxed-closures-unique-type-id.rs
@@ -16,6 +16,8 @@
 //    ReScope(63u32))
 //
 // This is a regression test for issue #17021.
+//
+// compile-flags: -g
 
 #![feature(unboxed_closures, overloaded_calls)]