diff --git a/lib/arm/translator.rb b/lib/arm/translator.rb
index b18aa8df..9e538845 100644
--- a/lib/arm/translator.rb
+++ b/lib/arm/translator.rb
@@ -40,7 +40,11 @@ module Arm
 
     def translate_SetSlot code
       # times 4 because arm works in bytes, but vm in words
-      ArmMachine.str( code.register ,  code.array , 4 * code.index )
+      if(code.index.is_a? Numeric)
+        ArmMachine.str( code.register ,  code.array , 4 * code.index )
+      else
+        ArmMachine.str( code.register ,  code.array , code.index )
+      end
     end
 
     def translate_FunctionCall code
diff --git a/lib/interpreter/interpreter.rb b/lib/interpreter/interpreter.rb
index 675113c5..70defd1d 100644
--- a/lib/interpreter/interpreter.rb
+++ b/lib/interpreter/interpreter.rb
@@ -130,7 +130,11 @@ module Interpreter
     def execute_SetSlot
       value = get_register( @instruction.register )
       object = get_register( @instruction.array )
-      object.set_internal( @instruction.index , value )
+      if( @instruction.index.is_a?(Numeric) )
+        object.set_internal( @instruction.index , value )
+      else
+        object.set_internal( get_register(@instruction.index) , value )
+      end
       trigger(:object_changed, @instruction.array , @instruction.index)
       true
     end
diff --git a/lib/register/boot.rb b/lib/register/boot.rb
index 293d880f..fb20340d 100644
--- a/lib/register/boot.rb
+++ b/lib/register/boot.rb
@@ -140,7 +140,7 @@ module Register
       # have to define some dummies, just for the other to compile
       # TODO go through the virtual parfait layer and adjust function names to what they really are
       obj = @space.get_class_by_name(:Object)
-      [:main , :get_internal ].each do |f|
+      [:main , :get_internal , :set_internal ].each do |f|
         obj.add_instance_method Builtin::Object.send(f , nil)
       end
       obj = @space.get_class_by_name(:Kernel)
diff --git a/lib/register/builtin/object.rb b/lib/register/builtin/object.rb
index ca939aa2..5f7884a2 100644
--- a/lib/register/builtin/object.rb
+++ b/lib/register/builtin/object.rb
@@ -15,7 +15,7 @@ module Register
 
         # self[index] basically. Index is the first arg
         # return is stored in return_value
-        # (this method returns a new method off course, like all builting)
+        # (this method returns a new method off course, like all builtin)
         def get_internal context
           compiler = Soml::Compiler.new.create_method(:Object , :get_internal , []).init_method
           source = "get_internal"
@@ -31,6 +31,24 @@ module Register
           return compiler.method
         end
 
+        # self[index] = val basically. Index is the first arg , vlaue the second
+        # no return
+        def set_internal context
+          compiler = Soml::Compiler.new.create_method(:Object , :set_internal , []).init_method
+          source = "set_internal"
+          #Load self by "calling" on_name
+          me = compiler.process( s(:name , :self) )
+          # Load the index
+          index = compiler.use_reg :Integer
+          compiler.add_code Register.get_slot(source , :message , Parfait::Message.get_indexed(1), index )
+          # Load the value
+          value = compiler.use_reg :Integer
+          compiler.add_code Register.get_slot(source , :message , Parfait::Message.get_indexed(2), value )
+          # do the set
+          compiler.add_code SetSlot.new( source , value , me , index)
+          return compiler.method
+        end
+
       end
       extend ClassMethods
     end
diff --git a/lib/register/instructions/set_slot.rb b/lib/register/instructions/set_slot.rb
index 223b94f9..37a4ef7b 100644
--- a/lib/register/instructions/set_slot.rb
+++ b/lib/register/instructions/set_slot.rb
@@ -22,7 +22,8 @@ module Register
       @register = register
       @array = array
       @index = index
-      raise "not integer #{index}" unless index.is_a? Numeric
+      raise "index 0 " if index == 0
+      raise "Not integer or reg #{index}" unless index.is_a?(Numeric) or RegisterValue.look_like_reg(index)
       raise "Not register #{register}" unless RegisterValue.look_like_reg(register)
       raise "Not register #{array}" unless RegisterValue.look_like_reg(array)
     end