diff --git a/libs/ardour/ardour/thawlist.h b/libs/ardour/ardour/thawlist.h
index eb551a28ce..e103f80e32 100644
--- a/libs/ardour/ardour/thawlist.h
+++ b/libs/ardour/ardour/thawlist.h
@@ -27,6 +27,7 @@ namespace ARDOUR {
 class LIBARDOUR_API ThawList : public RegionList
 {
 	public:
+		~ThawList ();
 		void add (boost::shared_ptr<Region> r);
 		void release ();
 };
diff --git a/libs/ardour/thawlist.cc b/libs/ardour/thawlist.cc
index 5e7c94c4c2..cf7e110a0c 100644
--- a/libs/ardour/thawlist.cc
+++ b/libs/ardour/thawlist.cc
@@ -23,6 +23,12 @@
 
 using namespace ARDOUR;
 
+ThawList::~ThawList ()
+{
+	assert (empty ()); // so far all lists are explicitly release()d
+	release ();
+}
+
 void
 ThawList::add (boost::shared_ptr<Region> r)
 {