diff -Naur thin-provisioning-tools-0.6.1.orig/thin-provisioning/restore_emitter.cc thin-provisioning-tools-0.6.1/thin-provisioning/restore_emitter.cc
--- thin-provisioning-tools-0.6.1.orig/thin-provisioning/restore_emitter.cc	2016-09-16 04:59:20.729894740 +0100
+++ thin-provisioning-tools-0.6.1/thin-provisioning/restore_emitter.cc	2016-09-16 05:00:30.089893981 +0100
@@ -142,7 +142,7 @@
 		bool device_exists(thin_dev_t dev) const {
 			uint64_t key[1] = {dev};
 			device_tree::maybe_value v = md_->details_->lookup(key);
-			return v;
+			return v.is_initialized();
 		}
 
 		metadata::ptr md_;
diff -Naur thin-provisioning-tools-0.6.1.orig/thin-provisioning/thin_pool.cc thin-provisioning-tools-0.6.1/thin-provisioning/thin_pool.cc
--- thin-provisioning-tools-0.6.1.orig/thin-provisioning/thin_pool.cc	2016-09-16 04:59:20.729894740 +0100
+++ thin-provisioning-tools-0.6.1/thin-provisioning/thin_pool.cc	2016-09-16 05:00:12.139894177 +0100
@@ -232,7 +232,7 @@
 thin_pool::device_exists(thin_dev_t dev) const
 {
 	uint64_t key[1] = {dev};
-	return md_->details_->lookup(key);
+	return md_->details_->lookup(key).is_initialized();
 }
 
 //----------------------------------------------------------------