--- a/netwerk/base/nsIIOService.idl
+++ b/netwerk/base/nsIIOService.idl
@@ -45,18 +45,18 @@ interface nsIIOService : nsISupports
      * This method constructs a new URI by determining the scheme of the
      * URI spec, and then delegating the construction of the URI to the
      * protocol handler for that scheme. QueryInterface can be used on
      * the resulting URI object to obtain a more specific type of URI.
      *
      * @see nsIProtocolHandler::newURI
      */
     nsIURI newURI(in AUTF8String aSpec,
-                  in string aOriginCharset,
-                  in nsIURI aBaseURI);
+                  [optional] in string aOriginCharset,
+                  [optional] in nsIURI aBaseURI);
 
     /**
      * This method constructs a new URI from a nsIFile.
      *
      * @param aFile specifies the file path
      * @return reference to a new nsIURI object
      *
      * Note: in the future, for perf reasons we should allow 

--- a/netwerk/base/nsIProtocolHandler.idl
+++ b/netwerk/base/nsIProtocolHandler.idl
@@ -82,18 +82,18 @@ interface nsIProtocolHandler : nsISuppor
      *                         no charset transformation from aSpec).
      * @param aBaseURI       - if null, aSpec must specify an absolute URI.
      *                         otherwise, aSpec may be resolved relative
      *                         to aBaseURI, depending on the protocol. 
      *                         If the protocol has no concept of relative 
      *                         URI aBaseURI will simply be ignored.
      */
     nsIURI newURI(in AUTF8String aSpec,
-                  in string aOriginCharset,
-                  in nsIURI aBaseURI);
+                  [optional] in string aOriginCharset,
+                  [optional] in nsIURI aBaseURI);
 
     /**
      * Constructs a new channel from the given URI for this protocol handler and
      * sets the loadInfo for the constructed channel.
      */
     nsIChannel newChannel2(in nsIURI aURI, in nsILoadInfo aLoadinfo);
 
     /**