diff --git a/Python/pystate.c b/Python/pystate.c
index ddb7d42..3eefa36 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -537,6 +537,23 @@
     autoInterpreterState = NULL;
 }
 
+/* Reset the TLS key - called by PyOS_AfterFork.
+ * This should not be necessary, but some - buggy - pthread implementations
+ * don't flush TLS on fork, see issue #10517.
+ */
+void
+_PyGILState_Reinit(void)
+{
+    PyThreadState *tstate = PyGILState_GetThisThreadState();
+    PyThread_delete_key(autoTLSkey);
+    if ((autoTLSkey = PyThread_create_key()) == -1)
+        Py_FatalError("Could not allocate TLS entry");
+
+    /* re-associate the current thread state with the new key */
+    if (PyThread_set_key_value(autoTLSkey, (void *)tstate) < 0)
+        Py_FatalError("Couldn't create autoTLSkey mapping");
+}
+
 /* When a thread state is created for a thread by some mechanism other than
    PyGILState_Ensure, it's important that the GILState machinery knows about
    it so it doesn't try to create another thread state for the thread (this is