Fix compiler warnings.

3 files changed, 6 insertions, 0 deletions

diff --git a/src/audioinputengine.h b/src/audioinputengine.h
index c17b964..c2d2e24 100644
--- a/src/audioinputengine.h
+++ b/src/audioinputengine.h
@@ -35,6 +35,8 @@
 
 class AudioInputEngine {
 public:
+  virtual ~AudioInputEngine() {}
+
   virtual bool init(Instruments &instruments) = 0;
 
   virtual void setParm(std::string parm, std::string value) = 0;
diff --git a/src/audiooutputengine.h b/src/audiooutputengine.h
index d2d2310..8b2b768 100644
--- a/src/audiooutputengine.h
+++ b/src/audiooutputengine.h
@@ -35,6 +35,8 @@
 
 class AudioOutputEngine {
 public:
+  virtual ~AudioOutputEngine() {}
+
   virtual bool init(Channels channels) = 0;
 
   virtual void setParm(std::string parm, std::string value) = 0;
diff --git a/src/events.h b/src/events.h
index 29cad22..a4adcee 100644
--- a/src/events.h
+++ b/src/events.h
@@ -40,6 +40,8 @@ typedef unsigned int timepos_t;
 
 class Event {
 public:
+  virtual ~Event() {}
+
   typedef enum {
     sample
   } type_t;