diff --git a/include/atomic b/include/atomic
index dc117e93a..a0245eb6a 100644
--- a/include/atomic
+++ b/include/atomic
@@ -1689,7 +1689,7 @@ typedef struct atomic_flag
 #endif // _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
 
     _LIBCPP_INLINE_VISIBILITY
-    atomic_flag(bool __b) _NOEXCEPT : __a_(__b) {}
+    atomic_flag(bool __b) _NOEXCEPT : __a_(__b) {} // EXTENSION
 
 #ifndef _LIBCPP_HAS_NO_DELETED_FUNCTIONS
     atomic_flag(const atomic_flag&) = delete;
diff --git a/test/std/atomics/atomics.flag/init03.pass.cpp b/test/libcxx/atomics/atomics.flag/init_bool.pass.cpp
similarity index 75%
rename from test/std/atomics/atomics.flag/init03.pass.cpp
rename to test/libcxx/atomics/atomics.flag/init_bool.pass.cpp
index 0910bc5ce..d7b172cd1 100644
--- a/test/std/atomics/atomics.flag/init03.pass.cpp
+++ b/test/libcxx/atomics/atomics.flag/init_bool.pass.cpp
@@ -20,6 +20,12 @@
 
 int main()
 {
-    std::atomic_flag f(false);
-    assert(f.test_and_set() == 0);
+    {
+        std::atomic_flag f(false);
+        assert(f.test_and_set() == 0);
+    }
+    {
+        std::atomic_flag f(true);
+        assert(f.test_and_set() == 1);
+    }
 }
diff --git a/test/std/atomics/atomics.flag/atomic_flag_clear.pass.cpp b/test/std/atomics/atomics.flag/atomic_flag_clear.pass.cpp
index 3a74e13fa..64093d639 100644
--- a/test/std/atomics/atomics.flag/atomic_flag_clear.pass.cpp
+++ b/test/std/atomics/atomics.flag/atomic_flag_clear.pass.cpp
@@ -22,13 +22,13 @@
 int main()
 {
     {
-        std::atomic_flag f(false);
+        std::atomic_flag f;
         f.test_and_set();
         atomic_flag_clear(&f);
         assert(f.test_and_set() == 0);
     }
     {
-        volatile std::atomic_flag f(false);
+        volatile std::atomic_flag f;
         f.test_and_set();
         atomic_flag_clear(&f);
         assert(f.test_and_set() == 0);
diff --git a/test/std/atomics/atomics.flag/atomic_flag_clear_explicit.pass.cpp b/test/std/atomics/atomics.flag/atomic_flag_clear_explicit.pass.cpp
index 046738445..e1a9349c9 100644
--- a/test/std/atomics/atomics.flag/atomic_flag_clear_explicit.pass.cpp
+++ b/test/std/atomics/atomics.flag/atomic_flag_clear_explicit.pass.cpp
@@ -22,37 +22,37 @@
 int main()
 {
     {
-        std::atomic_flag f(false);
+        std::atomic_flag f;
         f.test_and_set();
         atomic_flag_clear_explicit(&f, std::memory_order_relaxed);
         assert(f.test_and_set() == 0);
     }
     {
-        std::atomic_flag f(false);
+        std::atomic_flag f;
         f.test_and_set();
         atomic_flag_clear_explicit(&f, std::memory_order_release);
         assert(f.test_and_set() == 0);
     }
     {
-        std::atomic_flag f(false);
+        std::atomic_flag f;
         f.test_and_set();
         atomic_flag_clear_explicit(&f, std::memory_order_seq_cst);
         assert(f.test_and_set() == 0);
     }
     {
-        volatile std::atomic_flag f(false);
+        volatile std::atomic_flag f;
         f.test_and_set();
         atomic_flag_clear_explicit(&f, std::memory_order_relaxed);
         assert(f.test_and_set() == 0);
     }
     {
-        volatile std::atomic_flag f(false);
+        volatile std::atomic_flag f;
         f.test_and_set();
         atomic_flag_clear_explicit(&f, std::memory_order_release);
         assert(f.test_and_set() == 0);
     }
     {
-        volatile std::atomic_flag f(false);
+        volatile std::atomic_flag f;
         f.test_and_set();
         atomic_flag_clear_explicit(&f, std::memory_order_seq_cst);
         assert(f.test_and_set() == 0);
diff --git a/test/std/atomics/atomics.flag/clear.pass.cpp b/test/std/atomics/atomics.flag/clear.pass.cpp
index ea5ae45ae..65051af79 100644
--- a/test/std/atomics/atomics.flag/clear.pass.cpp
+++ b/test/std/atomics/atomics.flag/clear.pass.cpp
@@ -22,49 +22,49 @@
 int main()
 {
     {
-        std::atomic_flag f(false);
+        std::atomic_flag f;
         f.test_and_set();
         f.clear();
         assert(f.test_and_set() == 0);
     }
     {
-        std::atomic_flag f(false);
+        std::atomic_flag f;
         f.test_and_set();
         f.clear(std::memory_order_relaxed);
         assert(f.test_and_set() == 0);
     }
     {
-        std::atomic_flag f(false);
+        std::atomic_flag f;
         f.test_and_set();
         f.clear(std::memory_order_release);
         assert(f.test_and_set() == 0);
     }
     {
-        std::atomic_flag f(false);
+        std::atomic_flag f;
         f.test_and_set();
         f.clear(std::memory_order_seq_cst);
         assert(f.test_and_set() == 0);
     }
     {
-        volatile std::atomic_flag f(false);
+        volatile std::atomic_flag f;
         f.test_and_set();
         f.clear();
         assert(f.test_and_set() == 0);
     }
     {
-        volatile std::atomic_flag f(false);
+        volatile std::atomic_flag f;
         f.test_and_set();
         f.clear(std::memory_order_relaxed);
         assert(f.test_and_set() == 0);
     }
     {
-        volatile std::atomic_flag f(false);
+        volatile std::atomic_flag f;
         f.test_and_set();
         f.clear(std::memory_order_release);
         assert(f.test_and_set() == 0);
     }
     {
-        volatile std::atomic_flag f(false);
+        volatile std::atomic_flag f;
         f.test_and_set();
         f.clear(std::memory_order_seq_cst);
         assert(f.test_and_set() == 0);