diff --git a/lib/risc/builder.rb b/lib/risc/builder.rb
index a66890c0..bffdd2fb 100644
--- a/lib/risc/builder.rb
+++ b/lib/risc/builder.rb
@@ -33,9 +33,7 @@ module Risc
       name = name.to_s
       return @names[name] if @names.has_key?(name)
       if name == "message"
-        reg = Risc.message_reg
-        reg.builder = self
-        return reg
+        return Risc.message_reg.set_builder(self)
       end
       if name.index("label")
         reg = Risc.label( @source , "#{name}_#{object_id}")
@@ -44,8 +42,7 @@ module Risc
         raise "Must create (with !) before using #{name}" unless name[-1] == "!"
         name = name[0 ... -1]
         type = infer_type(name )
-        reg = @compiler.use_reg( type.object_class.name )
-        reg.builder = self
+        reg = @compiler.use_reg( type.object_class.name ).set_builder(self)
       end
       @names[name] = reg
       reg
@@ -129,8 +126,8 @@ module Risc
     # move a machine int from register "from" to a Parfait::Integer in register "to"
     # have to grab an integer from space and stick it in the "to" register first.
     def add_new_int( source , from, to )
-      to.builder = self    # esecially div10 comes in without having used builder
-      from.builder = self  # not named regs, different regs ==> silent errors
+      to.set_builder( self )    # esecially div10 comes in without having used builder
+      from.set_builder( self )  # not named regs, different regs ==> silent errors
       build do
         space! << Parfait.object_space
         to << space[:next_integer]
diff --git a/lib/risc/builtin/object.rb b/lib/risc/builtin/object.rb
index 016db9d0..04ed6e08 100644
--- a/lib/risc/builtin/object.rb
+++ b/lib/risc/builtin/object.rb
@@ -117,8 +117,8 @@ module Risc
         # This relies on linux to save and restore all registers
         #
         def save_message(builder)
-          r8 = RegisterValue.new( :r8 , :Message)
-          builder.add_transfer("save_message", Risc.message_reg , r8 )
+          r8 = RegisterValue.new( :r8 , :Message).set_builder(builder)
+          builder.build {r8 << message}
         end
 
         # restore the message that we save in r8
diff --git a/lib/risc/register_value.rb b/lib/risc/register_value.rb
index fad5d999..58bdfdfc 100644
--- a/lib/risc/register_value.rb
+++ b/lib/risc/register_value.rb
@@ -11,7 +11,7 @@ module Risc
 
     attr_reader :symbol , :type , :extra
 
-    attr_accessor :builder
+    attr_reader :builder
 
     # The first arg is a symbol :r0 - :r12
     # Second arg is the type, which may be given as the symbol of the class name
@@ -34,6 +34,15 @@ module Risc
       return :fixnum unless @type
       @type.class_name
     end
+
+    # allows to set the builder, which is mainly done by the builder
+    # but sometimes, eg in exit, one nneds to create the reg by hand and set
+    # return the RegisterValue for chaining in assignment
+    def set_builder( builder )
+      @builder = builder
+      self
+    end
+
     # using the registers type, resolve the slot to an index
     # Using the index and the register, add a SlotToReg to the instruction
     def resolve_and_add(slot , instruction , compiler)
diff --git a/test/risc/test_builder.rb b/test/risc/test_builder.rb
index 03120f8c..ee7cfc34 100644
--- a/test/risc/test_builder.rb
+++ b/test/risc/test_builder.rb
@@ -45,15 +45,13 @@ module Risc
       assert_equal Transfer , built.next.class
     end
     def test_returns_slot
-      r2 = RegisterValue.new(:r2 , :Message)
-      r2.builder = @builder
+      r2 = RegisterValue.new(:r2 , :Message).set_builder( @builder )
       built = @builder.build{ r2 << space![:next_message] }
       assert_equal SlotToReg , built.class
       assert_equal :r1 , built.array.symbol
     end
     def test_returns_slot_reverse
-      r2 = RegisterValue.new(:r2 , :Message)
-      r2.builder = @builder
+      r2 = RegisterValue.new(:r2 , :Message).set_builder( @builder )
       built = @builder.build{ r2 << space![:next_message] }
       assert_equal SlotToReg , built.class
       assert_equal :r1 , built.array.symbol
diff --git a/test/risc/test_register_value.rb b/test/risc/test_register_value.rb
index a2100bdc..48556f94 100644
--- a/test/risc/test_register_value.rb
+++ b/test/risc/test_register_value.rb
@@ -35,9 +35,14 @@ module Risc
       transfer = @r0 << @r1
       assert_equal Transfer , transfer.class
     end
+    def test_set_builder
+      reg = @r0.set_builder(FakeBuilder.new)
+      assert_equal RegisterValue , reg.class
+      assert reg.builder
+    end
     def test_calls_builder
       builder = FakeBuilder.new
-      @r0.builder = builder
+      @r0.set_builder( builder )
       @r0 << @r1
       assert_equal Transfer , builder.built.class
     end