Index: MutableStringOps.cs
===================================================================
--- MutableStringOps.cs	(revision 93)
+++ MutableStringOps.cs	(working copy)
@@ -1552,6 +1552,7 @@
             return self;
         }
 
+        [RubyMethod("intern", RubyMethodAttributes.PublicInstance)]
         [RubyMethod("to_sym", RubyMethodAttributes.PublicInstance)]
         public static SymbolId ToSym(MutableString/*!*/ self) {
             return SymbolTable.StringToId(self.ToString());