--- Modules/_ssl.c      (revision 26636)
+++ Modules/_ssl.c      (working copy)
@@ -1550,8 +1550,11 @@ static int _setup_ssl_threads(void) {
                                return 0;
                        }
                }
-               CRYPTO_set_locking_callback(_ssl_thread_locking_function);
-               CRYPTO_set_id_callback(_ssl_thread_id_function);
+
+               if (CRYPTO_get_locking_callback() == NULL)
+                       CRYPTO_set_locking_callback(_ssl_thread_locking_function);
+               if (CRYPTO_get_locking_callback() == NULL)
+                       CRYPTO_set_id_callback(_ssl_thread_id_function);
        }
        return 1;
 }