diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 8063c21..a9fc21f 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -6,7 +6,7 @@
 #undef Yield   /* undefine macro conflicting with <winbase.h> */
 #include "pycore_object.h"
 #include "pycore_pyerrors.h"
-#include "pycore_pystate.h"
+#include "pycore_pystate.h"      // _PyThreadState_GET()
 #include "pycore_tupleobject.h"
 
 _Py_IDENTIFIER(__builtins__);