diff --git a/flavor.gradle b/flavor.gradle
index 3d3d7ba1..02676e94 100644
--- a/flavor.gradle
+++ b/flavor.gradle
@@ -1,25 +1,25 @@
-def KEYSTORE_FILE = ""
-def KEYSTORE_FILE_PASSWORD = ""
-def KEYSTORE_ALIAS = ""
-def KEYSTORE_ALIAS_PASSWORD = ""
+def KEYSTORE_FILE = null
+def KEYSTORE_FILE_PASSWORD = null
+def KEYSTORE_ALIAS = null
+def KEYSTORE_ALIAS_PASSWORD = null
 
-def APPID_BUGLY_FOR_PER = ""
-def APPKEY_BUGLY_FOR_PER = ""
-def APPID_BUGLY_FOR_COM = ""
-def APPKEY_BUGLY_FOR_COM = ""
+def APPID_BUGLY_FOR_PER = null
+def APPKEY_BUGLY_FOR_PER = null
+def APPID_BUGLY_FOR_COM = null
+def APPKEY_BUGLY_FOR_COM = null
 
-def CDKEY_CLASS = ""
-def DEVELOPER_ID = ""
+def CDKEY_CLASS = null
+def DEVELOPER_ID = null
 
-def WANPWD_FORMAT = ""
-def WANPWD_PATTERN = ""
-def WANPWD_TYPE_CREATE_CDKEY = ""
-def WANPWD_TYPE_QQ = ""
-def WANPWD_TYPE_FESTIVAL = ""
-def WANPWD_TYPE_USERPAGE = ""
-def WANPWD_TYPE_CDKEY = ""
-def WANPWD_TYPE_WEB = ""
-def WANPWD_TYPE_ABOUTME = ""
+def WANPWD_FORMAT = null
+def WANPWD_PATTERN = null
+def WANPWD_TYPE_CREATE_CDKEY = null
+def WANPWD_TYPE_QQ = null
+def WANPWD_TYPE_FESTIVAL = null
+def WANPWD_TYPE_USERPAGE = null
+def WANPWD_TYPE_CDKEY = null
+def WANPWD_TYPE_WEB = null
+def WANPWD_TYPE_ABOUTME = null
 
 if (project.rootProject.file('local.properties').exists()) {
     Properties properties = new Properties()