diff --git a/lib/Domain/IGunHal.hpp b/lib/Domain/IGunHal.hpp
index 0cc1efc..0f6c27f 100644
--- a/lib/Domain/IGunHal.hpp
+++ b/lib/Domain/IGunHal.hpp
@@ -18,8 +18,9 @@
 
 class IGunHal {
 public:
-  virtual void isButton1Pressed() = 0;
-  virtual void isButton2Pressed() = 0;
+  virtual ~IGunHal() {}
+  virtual bool isButton1Pressed() = 0;
+  virtual bool isButton2Pressed() = 0;
   virtual void shortDelay() = 0;
   virtual void longDelay() = 0;
   virtual void ledOn() = 0;
@@ -27,6 +28,6 @@ class IGunHal {
   virtual void laserOn() = 0;
   virtual void laserOff() = 0;
   virtual void vibrationOn() = 0;
-  virtual void vibrationOff() = 0; 
-  virtual void deepSleep() = 0; 
+  virtual void vibrationOff() = 0;
+  virtual void deepSleep() = 0;
 };
\ No newline at end of file
diff --git a/lib/Domain/ITargetGui.hpp b/lib/Domain/ITargetGui.hpp
index efc4537..6439432 100644
--- a/lib/Domain/ITargetGui.hpp
+++ b/lib/Domain/ITargetGui.hpp
@@ -30,6 +30,8 @@ class ITargetGui {
     Five
   };
   
+  virtual ~ITargetGui() {}
+
   /**
    * Tell GUI a target has been hit
   */