diff --git a/translate/baidu/baidu_translate.py b/translate/baidu/baidu_translate.py
index a871766..6f99e34 100644
--- a/translate/baidu/baidu_translate.py
+++ b/translate/baidu/baidu_translate.py
@@ -17,13 +17,15 @@ class BaiduTranslator(Translator):
         self.url = endpoint + path
         self.appid = conf().get("baidu_translate_app_id")
         self.appkey = conf().get("baidu_translate_app_key")
+        if not self.appid or not self.appkey:
+            raise Exception("baidu translate appid or appkey not set")
 
     # For list of language codes, please refer to `https://api.fanyi.baidu.com/doc/21`, need to convert to ISO 639-1 codes
     def translate(self, query: str, from_lang: str = "", to_lang: str = "en") -> str:
         if not from_lang:
             from_lang = "auto"  # baidu suppport auto detect
         salt = random.randint(32768, 65536)
-        sign = self.make_md5(self.appid + query + str(salt) + self.appkey)
+        sign = self.make_md5("{}{}{}{}".format(self.appid, query, salt, self.appkey))
         headers = {"Content-Type": "application/x-www-form-urlencoded"}
         payload = {"appid": self.appid, "q": query, "from": from_lang, "to": to_lang, "salt": salt, "sign": sign}