diff --git a/entropy_src.h b/entropy_src.h
index c2ba4b7..8e7cbde 100644
--- a/entropy_src.h
+++ b/entropy_src.h
@@ -20,7 +20,9 @@ public:
 	EntropySrc() = default;
 	EntropySrc(const EntropySrc&) = delete;
 	EntropySrc& operator=(const EntropySrc&) = delete;
-	~EntropySrc() noexcept = default;
+
+protected:
+	virtual ~EntropySrc() noexcept = default;
 };
 
 } // namespace accumulator
diff --git a/event_adder.h b/event_adder.h
index 69d2266..0af2cbc 100644
--- a/event_adder.h
+++ b/event_adder.h
@@ -9,6 +9,9 @@ namespace accumulator {
 class EventAdder {
 public:
 	virtual void add(const std::vector<char>& e) = 0;
+
+protected:
+	virtual ~EventAdder() noexcept = default;
 };
 
 } // namespace accumulator