diff --git a/benchmark/rubinius/bm_lookuptable.rb b/benchmark/rubinius/bm_lookuptable.rb
index bf4373e89a..b90dd47be8 100644
--- a/benchmark/rubinius/bm_lookuptable.rb
+++ b/benchmark/rubinius/bm_lookuptable.rb
@@ -14,6 +14,7 @@ def make_symbol
   make_string.to_sym
 end
 
+LookupTable = Hash unless defined?(LookupTable)
 table = LookupTable.new
 hash = {}