diff --git a/lib/risc/instructions/slot_to_reg.rb b/lib/risc/instructions/slot_to_reg.rb
index 0ea8185b..2cb9decf 100644
--- a/lib/risc/instructions/slot_to_reg.rb
+++ b/lib/risc/instructions/slot_to_reg.rb
@@ -16,9 +16,12 @@ module Risc
   # Produce a SlotToReg instruction.
   # Array and to are registers
   # index may be a Symbol in which case is resolves with resolve_index.
-  def self.slot_to_reg( source , array , index , to)
-    raise "Not register #{array}" unless RegisterValue.look_like_reg(array)
+  def self.slot_to_reg( source , array , index )
+    raise "Register #{array}" if RegisterValue.look_like_reg(array.symbol)
     index = array.resolve_index(index) if index.is_a?(Symbol)
+    type = array.type_at(index)
+    #puts "Slot for #{array.symbol}@ index #{index} is #{type}"
+    to = RegisterValue.new( "#{array.symbol}.#{type.to_s.downcase}".to_sym , type )
     SlotToReg.new( source , array , index , to)
   end
 end
diff --git a/test/risc/instructions/test_slot_to_reg.rb b/test/risc/instructions/test_slot_to_reg.rb
new file mode 100644
index 00000000..3057a3f7
--- /dev/null
+++ b/test/risc/instructions/test_slot_to_reg.rb
@@ -0,0 +1,18 @@
+require_relative "../helper"
+
+module Risc
+  class TestSlotToReg < MiniTest::Test
+    def setup
+      Parfait.boot!({})
+    end
+    def slot
+      Risc.slot_to_reg("source" , Risc.message_named_reg , :type)
+    end
+    def test_slot
+      assert_equal SlotToReg , slot.class
+    end
+    def test_slot_reg
+      assert_equal :"message.type" , slot.register.symbol
+    end
+  end
+end
diff --git a/test/risc/test_callable_compiler.rb b/test/risc/test_callable_compiler.rb
index a9d357b9..02b7cbc8 100644
--- a/test/risc/test_callable_compiler.rb
+++ b/test/risc/test_callable_compiler.rb
@@ -29,9 +29,6 @@ module Risc
     def test_const
       assert_equal Array , @compiler.constants.class
     end
-    def test_use_reg
-      @compiler.use_reg(:Type)
-    end
   end
   class TestFakeCallableCompiler < MiniTest::Test
     def setup