diff --git a/lib/vool/builtin.rb b/lib/vool/builtin.rb
index 67dc69bf..1a2fdde6 100644
--- a/lib/vool/builtin.rb
+++ b/lib/vool/builtin.rb
@@ -6,9 +6,12 @@ module Vool
     end
 
     def self.load_builtin(loads)
+      return "class Space;def main(arg);return 0; end; end" if(loads == "Space.main")
+      raise "no preload #{loads}" unless builtin[loads]
       clazz , meth = loads.split(".")
-      "class #{clazz} #{derive(clazz)}; #{Vool::Builtin.builtin[loads]};end;"
+      "class #{clazz} #{derive(clazz)}; #{builtin[loads]};end;"
     end
+
     def self.derive(clazz) #must get derived classes rigth, so no mismatch
       case clazz
       when "Integer"
@@ -40,7 +43,6 @@ module Vool
         "Word.put" => "def putstring(at); X.putstring;end",
         "Word.set" => "def set_internal_byte(at, val); X.set_internal_byte;end",
         "Word.get" => "def get_internal_byte(at); X.get_internal_byte;end",
-        "Space.main" => "def main(args);return nil;end",
       }
     end
     def self.builtin_code
diff --git a/lib/vool/method_expression.rb b/lib/vool/method_expression.rb
index 4a5de92d..28e1210b 100644
--- a/lib/vool/method_expression.rb
+++ b/lib/vool/method_expression.rb
@@ -13,6 +13,10 @@ module Vool
     # Must pass in the actual Parfait class (default nil is just to conform to api)
     def to_parfait( clazz = nil )
       raise "No class given to method #{name}" unless clazz
+      if( method = clazz.get_instance_method(name))
+        #FIXME , should check arg_type, and if the same, clear method and ok
+        raise "Redefining #{clazz.name}.#{name} not supported #{method}"
+      end
       clazz.add_instance_method_for(name , make_arg_type , make_frame , body )
     end
 
diff --git a/test/mom/macro/test_init.rb b/test/mom/macro/test_init.rb
index 48421d1f..9a6a7043 100644
--- a/test/mom/macro/test_init.rb
+++ b/test/mom/macro/test_init.rb
@@ -4,8 +4,8 @@ module Mom
   module Builtin
     class TestObjectInitRisc < BootTest
       def setup
-        Parfait.boot!(Parfait.default_test_options)
-        get_compiler("Space",:main)
+        compiler = RubyX::RubyXCompiler.new(RubyX.default_test_options)
+        coll = compiler.ruby_to_mom( get_preload("Space.main") )
         @method = MomCollection.create_init_compiler
       end
       def test_mom_length
diff --git a/test/parfait/test_vool_method.rb b/test/parfait/test_vool_method.rb
index 1d6ac49e..0b7d9cf8 100644
--- a/test/parfait/test_vool_method.rb
+++ b/test/parfait/test_vool_method.rb
@@ -22,7 +22,7 @@ module Vool
     end
     def test_method
       clazz =  @clazz.to_parfait
-      assert_equal Parfait::VoolMethod , method.to_parfait(clazz).class
+      assert_equal Parfait::VoolMethod , clazz.get_instance_method(:main).class
     end
   end
 end
diff --git a/test/risc/interpreter/builtin/test_int_math.rb b/test/risc/interpreter/builtin/test_int_math.rb
index 24fba9da..0646279f 100644
--- a/test/risc/interpreter/builtin/test_int_math.rb
+++ b/test/risc/interpreter/builtin/test_int_math.rb
@@ -5,38 +5,45 @@ module Risc
     class IntMath < Minitest::Test
       include Ticker
       def setup
-        @preload = "all"
       end
 
       def test_add
+        @preload = "Integer.plus"
         run_main_return "5 + 5"
         assert_equal 10 , get_return
       end
       def test_minus
+        @preload = "Integer.minus"
         run_main_return "5 - 5"
         assert_equal 0 , get_return
       end
       def test_minus_neg
+        @preload = "Integer.minus"
         run_main_return "5 - 15"
         assert_equal( -10 , get_return)
       end
       def test_rshift
+        @preload = "Integer.rs"
         run_main_return "#{2**8} >> 3"
         assert_equal 2**5 , get_return
       end
       def test_lshift
+        @preload = "Integer.ls"
         run_main_return "#{2**8} << 3"
         assert_equal 2**11 , get_return
       end
       def test_div10
+        @preload = "Integer.div10"
         run_main_return "45.div10"
         assert_equal 4 , get_return
       end
       def test_div4
+        @preload = "Integer.div4"
         run_main_return "45.div4"
         assert_equal 11 , get_return
       end
       def test_mult
+        @preload = "Integer.mul"
         run_main_return "4 * 4"
         assert_equal 16 , get_return
       end
diff --git a/test/rubyx/macro/test_object_missing.rb b/test/rubyx/macro/test_object_missing.rb
index 31a93f7e..53e5d609 100644
--- a/test/rubyx/macro/test_object_missing.rb
+++ b/test/rubyx/macro/test_object_missing.rb
@@ -6,11 +6,6 @@ module RubyX
       include MacroHelper
       def source
         <<GET
-        class Space
-          def main(arg)
-            return
-          end
-        end
         class Object
           def method_missing(at)
             X.method_missing(:r1)
diff --git a/test/support/preloader.rb b/test/support/preloader.rb
index 645ed442..07c9744f 100644
--- a/test/support/preloader.rb
+++ b/test/support/preloader.rb
@@ -1,12 +1,12 @@
 module Preloader
   def get_preload(preload)
     return "" unless preload
-    preload = Vool::Builtin.builtin.keys.join(";") if(preload == "all" )
-    preload.split(";").collect do |loads|
-      raise "no preload #{loads}" unless Vool::Builtin.builtin[loads]
-      clazz , meth = loads.split(".")
-      "class #{clazz} #{Vool::Builtin.derive(clazz)}; #{Vool::Builtin.builtin[loads]};end;"
-    end.join
+    if( preload == "all" )
+      loading = Vool::Builtin.builtin.keys
+    else
+      loading = preload.split(";")
+    end
+    loading.collect { |loads| Vool::Builtin.load_builtin(loads)}.join(";") + ";"
   end
   def preload
     get_preload(@preload)
diff --git a/test/support/risc_interpreter.rb b/test/support/risc_interpreter.rb
index e1277ea5..d0b2c6cd 100644
--- a/test/support/risc_interpreter.rb
+++ b/test/support/risc_interpreter.rb
@@ -105,7 +105,7 @@ module Risc
     # use the input as it, compile and run it
     # input muts contain a Space.main, but may contain more classes and methods
     def run_input(input)
-      @string_input = preload + input
+      @string_input = input
       do_setup
       run_all
     end
diff --git a/test/vool/test_method_expression.rb b/test/vool/test_method_expression.rb
index 53bec976..8256b2a9 100644
--- a/test/vool/test_method_expression.rb
+++ b/test/vool/test_method_expression.rb
@@ -21,15 +21,28 @@ module Vool
       assert_raises{ method.to_parfait }
     end
     def test_method
-      clazz = @clazz.to_parfait
-      assert_equal Parfait::Class , clazz.class
-      meth = method.to_parfait(clazz)
-      assert_equal Parfait::VoolMethod , meth.class
-      assert_equal :main , meth.name
+      assert_equal Parfait::Class , @clazz.to_parfait.class
     end
     def test_is_instance_method
-      assert main = @clazz.to_parfait.get_instance_method(:main)
+      main = @clazz.to_parfait.get_instance_method(:main)
+      assert_equal Parfait::VoolMethod , main.class
+      assert_equal :main , main.name
     end
 
   end
+  class TestMethodExpressionDoubleDef < MiniTest::Test
+    include VoolCompile
+
+    def setup
+      Parfait.boot!(Parfait.default_test_options)
+      ruby_tree = Ruby::RubyCompiler.compile( as_main("a = 5") + ";" + as_main("a = 5") )
+      @clazz = ruby_tree.to_vool
+    end
+    def method
+      @clazz.body.first
+    end
+    def test_no_double
+      assert_raises {@clazz.to_parfait}
+    end
+  end
 end