diff --git a/lib/mom/instruction/message_setup.rb b/lib/mom/instruction/message_setup.rb
index cb6ef6d9..ba9c36f6 100644
--- a/lib/mom/instruction/message_setup.rb
+++ b/lib/mom/instruction/message_setup.rb
@@ -27,7 +27,7 @@ module Mom
     # Move method name, frame and arguemnt types from the method to the next_message
     # Get the message from Space and link it.
     def to_risc(compiler)
-      builder = compiler.builder(false, self)
+      builder = compiler.code_builder(self)
       build_with(builder)
     end
 
diff --git a/lib/mom/instruction/resolve_method.rb b/lib/mom/instruction/resolve_method.rb
index 95d7fa46..d3e0a3ee 100644
--- a/lib/mom/instruction/resolve_method.rb
+++ b/lib/mom/instruction/resolve_method.rb
@@ -35,7 +35,7 @@ module Mom
     def to_risc( compiler )
       name_ = @name
       cache_entry_ = @cache_entry
-      builder = compiler.builder(false, self)
+      builder = compiler.code_builder(self)
       builder.build do
         word << name_
         cache_entry << cache_entry_
diff --git a/lib/risc/builder.rb b/lib/risc/builder.rb
index 7634ffa7..48911166 100644
--- a/lib/risc/builder.rb
+++ b/lib/risc/builder.rb
@@ -2,9 +2,15 @@ module Risc
 
   # A Builder is used to generate code, either by using it's api, or dsl
   #
-  # The code that is generated can be added to the comiled method, ie to the compiler.
+  # There are two subclasses of Builder, depending of what one wants to do with the
+  # generated code.
+  #
+  # CompilerBuilder: The code is added to the method_compiler.
   # This is used to generate the builtin methods.
-  # Or the code can be stored up and returned. This is used in Mom::to_risc methods
+  #
+  # CodeBuilder: The code can be stored up and returned.
+  #              This is used in Mom::to_risc methods
+  #
   class Builder
 
     attr_reader :built , :compiler
@@ -12,10 +18,8 @@ module Risc
     # pass a compiler, to which instruction are added (usually)
     # second arg determines weather instructions are added (default true)
     # call build with a block to build
-    def initialize(compiler, auto_add , for_source)
+    def initialize(compiler, for_source)
       @compiler = compiler
-      @auto_add = auto_add
-      @built = nil
       @source = for_source
       @source_used = false
       @names = {}
@@ -60,6 +64,7 @@ module Risc
     # names (that ruby would resolve to a variable/method) are converted
     # to registers. << means assignment and [] is supported both on
     # L and R values (but only one at a time). R values may also be constants.
+    #
     # Basically this allows to create LoadConstant, RegToSlot, SlotToReg and
     # Transfer instructions with extremely readable code.
     # example:
@@ -68,21 +73,14 @@ module Risc
     #
     # build result is available as built, but also gets added to compiler, if the
     # builder is created with default args
+    #
     def build(&block)
       instance_eval(&block)
       @built
     end
 
-    # adding code to the builder either stores it in the built variable
-    # or adds it straight to the compiler.
-    # Depending on wether auto_add was given in construction.
     def add_code(ins)
-      return @compiler.add_code(ins) if @auto_add
-      if(@built)
-        @built << ins
-      else
-        @built = ins
-      end
+      raise "Must be implemented in subclass #{self}"
     end
 
     # move a machine int from register "from" to a Parfait::Integer in register "to"
@@ -213,5 +211,38 @@ module Risc
     return index
   end
 
+  class CodeBuilder < Builder
+
+    attr_reader :built
+    def initialize(compiler, for_source)
+      super
+      @built = nil
+    end
+
+    def build(&block)
+      super
+      @built
+    end
+
+    # CodeBuilder stores the code.
+    # The code can be access through the @built instance, and is returned
+    # from build method
+    def add_code(ins)
+      if(@built)
+        @built << ins
+      else
+        @built = ins
+      end
+    end
+  end
+
+  # A CompilerBuilder adds the generated code to the MethodCompiler.
+  #
+  class CompilerBuilder < Builder
+    # add code straight to the compiler
+    def add_code(ins)
+      return @compiler.add_code(ins)
+    end
+  end
 
 end
diff --git a/lib/risc/builtin/integer.rb b/lib/risc/builtin/integer.rb
index e404cabc..8a0c9936 100644
--- a/lib/risc/builtin/integer.rb
+++ b/lib/risc/builtin/integer.rb
@@ -8,7 +8,7 @@ module Risc
         def div4(context)
           source = "div4"
           compiler = compiler_for(:Integer,:div4 ,{})
-          builder = compiler.builder(true, compiler.method)
+          builder = compiler.compiler_builder(compiler.method)
           me = builder.add_known( :receiver )
           builder.reduce_int( source , me )
           two = compiler.use_reg :fixnum , 2
@@ -33,7 +33,7 @@ module Risc
         end
         def comparison( operator  )
           compiler = compiler_for(:Integer, operator ,{other: :Integer})
-          builder = compiler.builder(true, compiler.method)
+          builder = compiler.compiler_builder(compiler.method)
           me , other = builder.self_and_int_arg("#{operator} load receiver and arg")
           false_label = Risc.label(compiler.method , "false_label_#{builder.object_id.to_s(16)}")
           merge_label = Risc.label(compiler.method , "merge_label_#{builder.object_id.to_s(16)}")
@@ -63,7 +63,7 @@ module Risc
         end
         def operator_method( op_sym )
           compiler = compiler_for(:Integer, op_sym ,{other: :Integer})
-          builder = compiler.builder(true, compiler.method)
+          builder = compiler.compiler_builder(compiler.method)
           me , other = builder.self_and_int_arg(op_sym.to_s + "load receiver and arg")
           builder.reduce_int( op_sym.to_s + " fix me", me )
           builder.reduce_int( op_sym.to_s + " fix arg", other )
@@ -76,7 +76,7 @@ module Risc
         def div10( context )
           s = "div_10 "
           compiler = compiler_for(:Integer,:div10 ,{})
-          builder = compiler.builder(true, compiler.method)
+          builder = compiler.compiler_builder(compiler.method)
           #FIX: this could load receiver once, reduce and then transfer twice
           me = builder.add_known( :receiver )
           tmp = builder.add_known( :receiver )
diff --git a/lib/risc/builtin/object.rb b/lib/risc/builtin/object.rb
index 61aaafdf..0361dc57 100644
--- a/lib/risc/builtin/object.rb
+++ b/lib/risc/builtin/object.rb
@@ -9,7 +9,7 @@ module Risc
         # (this method returns a new method off course, like all builtin)
         def get_internal_word( context )
           compiler = compiler_for(:Object , :get_internal_word ,{at: :Integer})
-          builder = compiler.builder(true, compiler.method)
+          builder = compiler.compiler_builder(compiler.method)
           source = "get_internal_word"
           me , index = builder.self_and_int_arg(source)
           # reduce me to me[index]
@@ -25,7 +25,7 @@ module Risc
         def set_internal_word( context )
           compiler = compiler_for(:Object , :set_internal_word , {at: :Integer, :value => :Object} )
           source = "set_internal_word"
-          builder = compiler.builder(true, compiler.method)
+          builder = compiler.compiler_builder(compiler.method)
           me , index = builder.self_and_int_arg(source)
           value = builder.load_int_arg_at(source , 1)
           # do the set
@@ -38,7 +38,7 @@ module Risc
         # Even if it's just this one, sys_exit (later raise)
         def _method_missing( context )
           compiler = compiler_for(:Object,:method_missing ,{})
-          emit_syscall( compiler.builder(true, compiler.method) , :exit )
+          emit_syscall( compiler.compiler_builder(compiler.method) , :exit )
           return compiler.method
         end
 
@@ -48,7 +48,7 @@ module Risc
         def __init__ context
           compiler = MethodCompiler.compiler_for_class(:Object,:__init__ ,
                             Parfait::NamedList.type_for({}) , Parfait::NamedList.type_for({}))
-          builder = compiler.builder(true, compiler.method)
+          builder = compiler.compiler_builder(compiler.method)
           builder.build do
             space << Parfait.object_space
             message << space[:first_message]
@@ -87,7 +87,7 @@ module Risc
 
         def exit( context )
           compiler = compiler_for(:Object,:exit ,{})
-          builder = compiler.builder(true, compiler.method)
+          builder = compiler.compiler_builder(compiler.method)
           exit_sequence(builder)
           return compiler.method
         end
diff --git a/lib/risc/builtin/word.rb b/lib/risc/builtin/word.rb
index 22667512..51e14101 100644
--- a/lib/risc/builtin/word.rb
+++ b/lib/risc/builtin/word.rb
@@ -6,7 +6,7 @@ module Risc
 
         def putstring( context)
           compiler = compiler_for(:Word , :putstring ,{})
-          builder = compiler.builder(true, compiler.method)
+          builder = compiler.compiler_builder(compiler.method)
           builder.add_slot_to_reg( "putstring" , :message , :receiver , :new_message )
           index = Parfait::Word.get_length_index
           reg = RegisterValue.new(:r2 , :Integer)
@@ -21,7 +21,7 @@ module Risc
         def get_internal_byte( context)
           compiler = compiler_for(:Word , :get_internal_byte , {at: :Integer})
           source = "get_internal_byte"
-          builder = compiler.builder(true, compiler.method)
+          builder = compiler.compiler_builder(compiler.method)
           me , index = builder.self_and_int_arg(source)
           builder.reduce_int( source + " fix arg", index )
           # reduce me to me[index]
@@ -39,7 +39,7 @@ module Risc
         def set_internal_byte( context )
           compiler = compiler_for(:Word, :set_internal_byte , {at: :Integer , :value => :Integer} )
           source = "set_internal_byte"
-          builder = compiler.builder(true, compiler.method)
+          builder = compiler.compiler_builder(compiler.method)
           me , index = builder.self_and_int_arg(source)
           value = builder.load_int_arg_at(source , 1 )
           builder.reduce_int( source + " fix me", value )
diff --git a/lib/risc/method_compiler.rb b/lib/risc/method_compiler.rb
index a328558d..b3e2e84f 100644
--- a/lib/risc/method_compiler.rb
+++ b/lib/risc/method_compiler.rb
@@ -106,11 +106,16 @@ module Risc
       builder.build(&block)
     end
 
-    # return a new builder that uses this compiler
-    # must specify whether to add code automatically to compiler
-    # second arg is the source for which to build, either method or mom::instruction
-    def builder( auto_add , source)
-      Builder.new(self , auto_add , source)
+    # return a new code builder that uses this compiler
+    # CodeBuilder returns code after building
+    def code_builder( source)
+      CodeBuilder.new(self , source)
+    end
+
+    # return a CompilerBuilder
+    # CompilerBuilder adds the generated code to the compiler
+    def compiler_builder( source)
+      CompilerBuilder.new(self , source)
     end
   end
 end
diff --git a/test/risc/test_builder.rb b/test/risc/test_builder.rb
index 903be235..e7522ba5 100644
--- a/test/risc/test_builder.rb
+++ b/test/risc/test_builder.rb
@@ -1,12 +1,12 @@
 require_relative "../helper"
 
 module Risc
-  class TestBuilderFalse < MiniTest::Test
+  class TestCodeBuilder < MiniTest::Test
 
     def setup
       Risc.machine.boot
       init = Parfait.object_space.get_init
-      @builder = Risc::MethodCompiler.new( init ).builder(false , init)
+      @builder = Risc::MethodCompiler.new( init ).code_builder(init)
       @label = Risc.label("source","name")
     end
     def test_has_build
@@ -97,12 +97,12 @@ module Risc
       assert_equal :Space , op.left.type
     end
   end
-  class TestBuilderTrue < MiniTest::Test
+  class TestCompilerBuilder < MiniTest::Test
 
     def setup
       Risc.machine.boot
       @init = Parfait.object_space.get_init
-      @builder = Risc::MethodCompiler.new( @init ).builder(true, @init)
+      @builder = Risc::MethodCompiler.new( @init ).compiler_builder(@init)
     end
     def test_inserts_built
       r1 = RegisterValue.new(:r1 , :Space)