diff --git a/libraries/ESP8266WebServer/README.rst b/libraries/ESP8266WebServer/README.rst
index 00a3813a84..0dcf68b516 100644
--- a/libraries/ESP8266WebServer/README.rst
+++ b/libraries/ESP8266WebServer/README.rst
@@ -96,7 +96,7 @@ Getting information about request arguments
   int args();
   bool hasArg();
 
-``arg`` - get request argument value
+``arg`` - get request argument value, use ``arg("plain")`` to get POST body
 	
 ``argName`` - get request argument name