diff --git a/include/__config b/include/__config
index 118e3bd..d7ecdcf 100644
--- a/include/__config
+++ b/include/__config
@@ -583,6 +583,7 @@
 
 #define _LIBCPP_TYPE_VIS            _LIBCPP_DLL_VIS
 #define _LIBCPP_FUNC_VIS            _LIBCPP_DLL_VIS
+#define _LIBCPP_EXTERN_VIS          _LIBCPP_DLL_VIS
 #define _LIBCPP_EXCEPTION_ABI       _LIBCPP_DLL_VIS
 #define _LIBCPP_HIDDEN
 #define _LIBCPP_TEMPLATE_VIS
@@ -636,6 +637,10 @@
 # define _LIBCPP_FUNC_VIS_ONLY _LIBCPP_FUNC_VIS
 #endif
 
+#ifndef _LIBCPP_EXTERN_VIS
+# define _LIBCPP_EXTERN_VIS
+#endif
+
 #ifndef _LIBCPP_OVERRIDABLE_FUNC_VIS
 # define _LIBCPP_OVERRIDABLE_FUNC_VIS _LIBCPP_FUNC_VIS
 #endif
diff --git a/include/__debug b/include/__debug
index d95e339..d01bacd 100644
--- a/include/__debug
+++ b/include/__debug
@@ -74,7 +74,7 @@
 
 /// __libcpp_debug_function - The handler function called when a _LIBCPP_ASSERT
 ///    fails.
-extern __libcpp_debug_function_type __libcpp_debug_function;
+extern _LIBCPP_EXTERN_VIS __libcpp_debug_function_type __libcpp_debug_function;
 
 /// __libcpp_abort_debug_function - A debug handler that aborts when called.
 _LIBCPP_NORETURN _LIBCPP_FUNC_VIS