diff --git a/pyttsx3/drivers/nsss.py b/pyttsx3/drivers/nsss.py
index 6cf5f81..412764e 100644
--- a/pyttsx3/drivers/nsss.py
+++ b/pyttsx3/drivers/nsss.py
@@ -99,6 +99,8 @@ def setProperty(self, name, value):
 
     @objc.python_method
     def save_to_file(self, text, filename):
+        self._proxy.setBusy(True)
+        self._completed = True
         url = Foundation.NSURL.fileURLWithPath_(filename)
         self._tts.startSpeakingString_toURL_(text, url)