diff --git a/lib/ostruct.rb b/lib/ostruct.rb
index f51eb7b5db..35047f1cff 100644
--- a/lib/ostruct.rb
+++ b/lib/ostruct.rb
@@ -174,9 +174,8 @@ class OpenStruct
   protected :new_ostruct_member
 
   def method_missing(mid, *args) # :nodoc:
-    mname = mid.id2name
     len = args.length
-    if mname.chomp!('=')
+    if mname = mid[/.*(?==\z)/m]
       if len != 1
         raise ArgumentError, "wrong number of arguments (#{len} for 1)", caller(1)
       end