diff --git a/libs/ardour/ardour/audio_backend.h b/libs/ardour/ardour/audio_backend.h
index 323b5017de..e4add4e92b 100644
--- a/libs/ardour/ardour/audio_backend.h
+++ b/libs/ardour/ardour/audio_backend.h
@@ -190,7 +190,7 @@ class LIBARDOUR_API AudioBackend : public PortEngine {
     virtual int set_device_name (const std::string&) = 0;
     /** Deinitialize and destroy current device
      */
-	virtual int drop_device() {};
+    virtual int drop_device() { return 0; };
     /** Set the sample rate to be used
      */
     virtual int set_sample_rate (float) = 0;