diff --git a/lib/interpreter/interpreter.rb b/lib/interpreter/interpreter.rb
index 711ff16c..660d1314 100644
--- a/lib/interpreter/interpreter.rb
+++ b/lib/interpreter/interpreter.rb
@@ -120,7 +120,12 @@ module Interpreter
 
     def execute_GetSlot
       object = object_for( @instruction.array )
-      value = object.internal_object_get( @instruction.index )
+      if( @instruction.index.is_a?(Numeric) )
+        index = @instruction.index
+      else
+        index = get_register(@instruction.index)
+      end
+      value = object.internal_object_get( index )
       #value = value.object_id unless value.is_a? Fixnum
       set_register( @instruction.register , value )
       true
@@ -192,7 +197,7 @@ module Interpreter
       else
         raise "unimplemented  '#{@instruction.operator}' #{@instruction}"
       end
-      ## result not over 2**62  => overflow 
+      ## result not over 2**62  => overflow
       log.debug "#{@instruction} == #{result}   (#{left}|#{right})"
       right = set_register(@instruction.left , result)
       true
diff --git a/lib/register/instructions/get_slot.rb b/lib/register/instructions/get_slot.rb
index a921178b..0426b598 100644
--- a/lib/register/instructions/get_slot.rb
+++ b/lib/register/instructions/get_slot.rb
@@ -23,8 +23,8 @@ module Register
       @array = array
       @index = index
       @register = register
-      raise "index 0 " if index == 0 
-      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