diff --git a/libs/ardour/vst3_host.cc b/libs/ardour/vst3_host.cc
index 5f02c743ef..c491dee88d 100644
--- a/libs/ardour/vst3_host.cc
+++ b/libs/ardour/vst3_host.cc
@@ -891,6 +891,7 @@ ROMStream::ROMStream (IBStream& src, TSize offset, TSize size)
 	: _stream (src)
 	, _offset (offset)
 	, _size   (size)
+	, _pos   (size)
 {
 	_stream.addRef ();
 }