diff --git a/include/__locale b/include/__locale
index 90dcad3..538bf7a 100644
--- a/include/__locale
+++ b/include/__locale
@@ -15,6 +15,7 @@
 #include <__memory/shared_ptr.h> // __shared_count
 #include <__mutex/once_flag.h>
 #include <__type_traits/make_unsigned.h>
+#include <atomic>
 #include <cctype>
 #include <clocale>
 #include <cstdint>
@@ -154,8 +155,7 @@ private:
 
 class _LIBCPP_EXPORTED_FROM_ABI locale::id
 {
-    once_flag      __flag_;
-    int32_t        __id_;
+    std::atomic<int32_t>        __id_;
 
     static int32_t __next_id;
 public: