bpo-11410: Standardize and use symbol visibility attributes across POSIX and Windows. (GH-16347)

diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 6089086..7025058 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -57,7 +57,7 @@
 extern "C" {
 #endif
 
-extern grammar _PyParser_Grammar; /* From graminit.c */
+extern Py_EXPORTED_SYMBOL grammar _PyParser_Grammar; /* From graminit.c */
 
 /* Forward */
 static void flush_io(void);