--- a/dom/bindings/Codegen.py
+++ b/dom/bindings/Codegen.py
@@ -3548,18 +3548,18 @@ def instantiateJSToNativeConversion(info
         declArgs = None
 
     result = CGList([], "\n")
     # Make a copy of "replacements" since we may be about to start modifying it
     replacements = dict(replacements)
     originalHolderName = replacements["holderName"]
     if holderType is not None:
         if dealWithOptional:
-            replacements["holderName"] = "%s.Value()" % originalHolderName
-            holderType = CGTemplatedType("Optional", holderType)
+            replacements["holderName"] = "%s.ref()" % originalHolderName
+            holderType = CGTemplatedType("Maybe", holderType)
             holderCtorArgs = None
         elif holderArgs is not None:
             holderCtorArgs = CGWrapper(holderArgs, pre="(", post=")")
         else:
             holderCtorArgs = None
         result.append(
             CGList([holderType, CGGeneric(" "),
                     CGGeneric(originalHolderName),
@@ -3587,17 +3587,17 @@ def instantiateJSToNativeConversion(info
     if argcAndIndex is not None:
         if dealWithOptional:
             declConstruct = CGIndenter(
                 CGGeneric("%s.Construct(%s);" %
                           (originalDeclName,
                            declArgs.define() if declArgs else "")))
             if holderType is not None:
                 holderConstruct = CGIndenter(
-                    CGGeneric("%s.Construct(%s);" %
+                    CGGeneric("%s.construct(%s);" %
                               (originalHolderName,
                                holderArgs.define() if holderArgs else "")))
             else:
                 holderConstruct = None
         else:
             declConstruct = None
             holderConstruct = None