diff --git a/tests/run-pass/threadleak_ignored.rs b/tests/run-pass/threadleak_ignored.rs
index 14a7449f339..840fbc1ebcb 100644
--- a/tests/run-pass/threadleak_ignored.rs
+++ b/tests/run-pass/threadleak_ignored.rs
@@ -1,3 +1,4 @@
+// ignore-windows: Concurrency on Windows is not supported yet.
 // compile-flags: -Zmiri-ignore-leaks
 
 //! Test that leaking threads works, and that their destructors are not executed.