diff --git a/test/thread/thread.mutex/thread.lock/thread.lock.unique/thread.lock.unique.cons/mutex_try_to_lock.pass.cpp b/test/thread/thread.mutex/thread.lock/thread.lock.unique/thread.lock.unique.cons/mutex_try_to_lock.pass.cpp
index 52815071..b6c64f50 100644
--- a/test/thread/thread.mutex/thread.lock/thread.lock.unique/thread.lock.unique.cons/mutex_try_to_lock.pass.cpp
+++ b/test/thread/thread.mutex/thread.lock/thread.lock.unique/thread.lock.unique.cons/mutex_try_to_lock.pass.cpp
@@ -48,7 +48,6 @@ void f()
             break;
     }
     time_point t1 = Clock::now();
-    m.unlock();
     ns d = t1 - t0 - ms(250);
     assert(d < ms(200));  // within 200ms
 }