diff --git a/lib/parfait/indexed.rb b/lib/parfait/indexed.rb
index abd41fa1..ed71ac26 100644
--- a/lib/parfait/indexed.rb
+++ b/lib/parfait/indexed.rb
@@ -166,7 +166,7 @@ module Parfait
             grow_to(index)
           end
           # start one higher than offset, which is where the length is
-          internal_object_set( index + 1 + offset, value)
+          internal_object_set( index + offset, value)
         end
 
         # set the value at index.
@@ -176,7 +176,7 @@ module Parfait
           ret = nil
           if(index <= self.get_length)
             # start one higher than offset, which is where the length is
-            ret = internal_object_get(index + offset + 1)
+            ret = internal_object_get(index + offset )
           end
           ret
         end
diff --git a/lib/register/instructions/get_slot.rb b/lib/register/instructions/get_slot.rb
index 2abc0a4b..a921178b 100644
--- a/lib/register/instructions/get_slot.rb
+++ b/lib/register/instructions/get_slot.rb
@@ -23,6 +23,7 @@ module Register
       @array = array
       @index = index
       @register = register
+      raise "index 0 " if index == 0 
       raise "not integer #{index}" unless index.is_a? Numeric
       raise "Not register #{register}" unless RegisterValue.look_like_reg(register)
       raise "Not register #{array}" unless RegisterValue.look_like_reg(array)
diff --git a/test/parfait/test_message.rb b/test/parfait/test_message.rb
index 56cca1b0..1cf75458 100644
--- a/test/parfait/test_message.rb
+++ b/test/parfait/test_message.rb
@@ -31,6 +31,10 @@ class TestMessage < MiniTest::Test
     @mess.push :name
     assert_equal 1 , @mess.internal_object_get(9)
   end
+  def test_get_internal
+    @mess.push :name
+    assert_equal :name , @mess.internal_object_get(10)
+  end
 
   def test_get
     index = @mess.push :name