diff --git a/include/__config b/include/__config
index 682b990..e49adb4 100644
--- a/include/__config
+++ b/include/__config
@@ -1097,6 +1097,14 @@
        _LIBCPP_HAS_NO_THREADS is defined.
 #endif
 
+#if defined(__STDCPP_THREADS__) && defined(_LIBCPP_HAS_NO_THREADS)
+#error _LIBCPP_HAS_NO_THREADS cannot be set when __STDCPP_THREADS__ is set.
+#endif
+
+#if !defined(_LIBCPP_HAS_NO_THREADS) && !defined(__STDCPP_THREADS__)
+#define __STDCPP_THREADS__ 1
+#endif
+
 // The glibc and Bionic implementation of pthreads implements
 // pthread_mutex_destroy as nop for regular mutexes. Additionally, Win32
 // mutexes have no destroy mechanism.
diff --git a/include/thread b/include/thread
index 3d8d2ac..4277bc9 100644
--- a/include/thread
+++ b/include/thread
@@ -14,8 +14,6 @@
 
     thread synopsis
 
-#define __STDCPP_THREADS__ __cplusplus
-
 namespace std
 {
 
@@ -107,8 +105,6 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-#define __STDCPP_THREADS__ __cplusplus
-
 #ifdef _LIBCPP_HAS_NO_THREADS
 #error <thread> is not supported on this single threaded system
 #else // !_LIBCPP_HAS_NO_THREADS
diff --git a/test/std/thread/macro.pass.cpp b/test/std/thread/macro.pass.cpp
index 0c16a0d..5d24d5f 100644
--- a/test/std/thread/macro.pass.cpp
+++ b/test/std/thread/macro.pass.cpp
@@ -10,7 +10,7 @@
 
 // <thread>
 
-// #define __STDCPP_THREADS__ __cplusplus
+// #define __STDCPP_THREADS__ 1
 
 #include <thread>
 
@@ -20,6 +20,8 @@
 {
 #ifndef __STDCPP_THREADS__
 #error __STDCPP_THREADS__ is not defined
+#elif __STDCPP_THREADS__ != 1
+#error __STDCPP_THREADS__ has the wrong value
 #endif
 
   return 0;