diff --git a/Misc/NEWS b/Misc/NEWS
index 6f12bce..285e8a4 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,9 @@
 Core and builtins
 -----------------
 
+- Make _PyGILState_NoteThreadState() static, it was not used anywhere
+  outside of pystate.c and should not be necessary.
+
 - Bug #1542051: Exceptions now correctly call PyObject_GC_UnTrack.
   Also make sure that every exception class has __module__ set to
   'exceptions'.
diff --git a/Python/pystate.c b/Python/pystate.c
index f591a59..639278f 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -309,9 +309,14 @@
 	*/
 #if defined(Py_DEBUG) && defined(WITH_THREAD)
 	if (newts) {
+		/* This can be called from PyEval_RestoreThread(). Similar
+		   to it, we need to ensure errno doesn't change.
+		*/
+		int err = errno;
 		PyThreadState *check = PyGILState_GetThisThreadState();
 		if (check && check->interp == newts->interp && check != newts)
 			Py_FatalError("Invalid thread state for this thread");
+		errno = err;
 	}
 #endif
 	return oldts;
@@ -504,7 +509,7 @@
    it so it doesn't try to create another thread state for the thread (this is
    a better fix for SF bug #1010677 than the first one attempted).
 */
-void
+static void
 _PyGILState_NoteThreadState(PyThreadState* tstate)
 {
 	/* If autoTLSkey is 0, this must be the very first threadstate created