diff --git a/FlippR-Driver/src/utility/OutputGPIOInterface.h b/FlippR-Driver/src/utility/OutputGPIOInterface.h
index 77e244c..94c9501 100644
--- a/FlippR-Driver/src/utility/OutputGPIOInterface.h
+++ b/FlippR-Driver/src/utility/OutputGPIOInterface.h
@@ -27,8 +27,13 @@ class OutputGPIOInterface : public GPIOInterface
 public:
   virtual ~OutputGPIOInterface() = default;
 
-  void activate_output_item(output::items::IOutputItem *item);
-  void deactivate_output_item(output::items::IOutputItem *item);
+  void activate_output_item(output::items::ISound *sound);
+  void activate_output_item(output::items::ILamp *lamp);
+  void activate_output_item(output::items::ISolenoid *solenoid);
+
+  void deactivate_output_item(output::items::ISound *sound);
+  void deactivate_output_item(output::items::ILamp *lamp);
+  void deactivate_output_item(output::items::ISolenoid *solenoid);
 
   void write_display(output::items::IDisplay &display);