diff --git a/common/rdr/FdInStream.h b/common/rdr/FdInStream.h
index 5d9598c..b4c8765 100644
--- a/common/rdr/FdInStream.h
+++ b/common/rdr/FdInStream.h
@@ -30,6 +30,7 @@
   class FdInStreamBlockCallback {
   public:
     virtual void blockCallback() = 0;
+    virtual ~FdInStreamBlockCallback() {}
   };
 
   class FdInStream : public InStream {