diff --git a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/variadic_adopt_lock.pass.cpp b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/variadic_adopt_lock.pass.cpp
index 0de002a2a420..840af6788d04 100644
--- a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/variadic_adopt_lock.pass.cpp
+++ b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/variadic_adopt_lock.pass.cpp
@@ -25,7 +25,7 @@ struct TestMutex {
     TestMutex() = default;
 
     void lock() { assert(!locked); locked = true; }
-    bool try_lock() { if (locked) return false; return locked = true; }
+    bool try_lock() { if (locked) return false; locked = true; return true; }
     void unlock() { assert(locked); locked = false; }
 
     TestMutex(TestMutex const&) = delete;
diff --git a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/variadic_mutex.pass.cpp b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/variadic_mutex.pass.cpp
index 68f84fe32de3..4910d837cae3 100644
--- a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/variadic_mutex.pass.cpp
+++ b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/variadic_mutex.pass.cpp
@@ -28,7 +28,7 @@ struct TestMutex {
     ~TestMutex() { assert(!locked); }
 
     void lock() { assert(!locked); locked = true; }
-    bool try_lock() { if (locked) return false; return locked = true; }
+    bool try_lock() { if (locked) return false; locked = true; return true; }
     void unlock() { assert(locked); locked = false; }
 
     TestMutex(TestMutex const&) = delete;