diff --git a/libs/pbd/pbd/ringbuffer.h b/libs/pbd/pbd/ringbuffer.h
index f71d05afe8..48d0036933 100644
--- a/libs/pbd/pbd/ringbuffer.h
+++ b/libs/pbd/pbd/ringbuffer.h
@@ -125,6 +125,9 @@ protected:
 	mutable gint write_idx;
 	mutable gint read_idx;
 	guint size_mask;
+
+private:
+	RingBuffer (RingBuffer const&);
 };
 
 template<class T> /*LIBPBD_API*/ guint
diff --git a/libs/pbd/pbd/ringbufferNPT.h b/libs/pbd/pbd/ringbufferNPT.h
index cfb4a91b05..174d15e9b9 100644
--- a/libs/pbd/pbd/ringbufferNPT.h
+++ b/libs/pbd/pbd/ringbufferNPT.h
@@ -120,6 +120,9 @@ class /*LIBPBD_API*/ RingBufferNPT
 	size_t size;
 	mutable gint write_ptr;
 	mutable gint read_ptr;
+
+private:
+	RingBufferNPT (RingBufferNPT const&);
 };
 
 template<class T> /*LIBPBD_API*/ size_t