diff --git a/src/collection_notifications.hpp b/src/collection_notifications.hpp
index 919e8b465..bbd41e534 100644
--- a/src/collection_notifications.hpp
+++ b/src/collection_notifications.hpp
@@ -126,6 +126,7 @@ class CollectionChangeCallback {
 
 private:
     struct Base {
+        virtual ~Base() {}
         virtual void before(CollectionChangeSet const&)=0;
         virtual void after(CollectionChangeSet const&)=0;
         virtual void error(std::exception_ptr)=0;