diff --git a/emitter.h b/emitter.h
index 8505995..ff136a6 100644
--- a/emitter.h
+++ b/emitter.h
@@ -43,8 +43,8 @@ namespace thin_provisioning {
 		virtual void end_named_mapping() = 0;
 
 		virtual void identifier(std::string const &name) = 0;
-		virtual void range_map(uint64_t origin_begin, uint64_t data_begin, uint64_t len) = 0;
-		virtual void single_map(uint64_t origin_block, uint64_t data_block) = 0;
+		virtual void range_map(uint64_t origin_begin, uint64_t data_begin, uint32_t time, uint64_t len) = 0;
+		virtual void single_map(uint64_t origin_block, uint64_t data_block, uint32_t time) = 0;
 	};
 }
 
diff --git a/human_readable_format.cc b/human_readable_format.cc
index 536ccc5..6fea41f 100644
--- a/human_readable_format.cc
+++ b/human_readable_format.cc
@@ -59,17 +59,20 @@ namespace {
 			out_ << "identifier: " << name << endl;
 		}
 
-		void range_map(uint64_t origin_begin, uint64_t data_begin, uint64_t len) {
+		void range_map(uint64_t origin_begin, uint64_t data_begin, uint32_t time, uint64_t len) {
 			out_ << "    (" << origin_begin
 			     << ".." << origin_begin + len - 1
 			     << ") -> (" << data_begin
 			     << ".." << data_begin + len - 1
-			     << ")" << endl;
+			     << "), "
+			     << time
+			     << endl;
 		}
 
-		void single_map(uint64_t origin_block, uint64_t data_block) {
+		void single_map(uint64_t origin_block, uint64_t data_block, uint32_t time) {
 			out_ << "    " << origin_block
 			     << " -> " << data_block
+			     << ", " << time
 			     << endl;
 		}
 
diff --git a/metadata_dumper.cc b/metadata_dumper.cc
index b60841b..851310d 100644
--- a/metadata_dumper.cc
+++ b/metadata_dumper.cc
@@ -32,7 +32,8 @@ namespace {
 		bool visit_leaf(unsigned level, bool sub_root, boost::optional<uint64_t> maybe_key,
 				btree_detail::node_ref<block_traits> const &n) {
 			for (unsigned i = 0; i < n.get_nr_entries(); i++) {
-				add_mapping(n.key_at(i), n.value_at(i).block_);
+				block_time bt = n.value_at(i);
+				add_mapping(n.key_at(i), bt.block_, bt.time_);
 			}
 
 			return true;
@@ -44,9 +45,10 @@ namespace {
 		}
 
 	private:
-		void start_mapping(uint64_t origin_block, uint64_t dest_block) {
+		void start_mapping(uint64_t origin_block, uint64_t dest_block, uint32_t time) {
 			origin_start_ = origin_block;
 			dest_start_ = dest_block;
+			time_ = time;
 			len_ = 1;
 			in_range_ = true;
 		}
@@ -54,25 +56,26 @@ namespace {
 		void end_mapping() {
 			if (in_range_) {
 				if (len_ == 1)
-					e_->single_map(origin_start_, dest_start_);
+					e_->single_map(origin_start_, dest_start_, time_);
 				else
-					e_->range_map(origin_start_, dest_start_, len_);
+					e_->range_map(origin_start_, dest_start_, time_, len_);
 
 				in_range_ = false;
 			}
 		}
 
-		void add_mapping(uint64_t origin_block, uint64_t dest_block) {
+		void add_mapping(uint64_t origin_block, uint64_t dest_block, uint32_t time) {
 			if (!in_range_)
-				start_mapping(origin_block, dest_block);
+				start_mapping(origin_block, dest_block, time);
 
 			else if (origin_block == origin_start_ + len_ &&
-				 dest_block == dest_start_ + len_)
+				 dest_block == dest_start_ + len_ &&
+				 time == time_)
 				len_++;
 
 			else {
 				end_mapping();
-				start_mapping(origin_block, dest_block);
+				start_mapping(origin_block, dest_block, time);
 			}
 		}
 
@@ -83,6 +86,7 @@ namespace {
 
 		bool in_range_;
 		uint64_t origin_start_, dest_start_, len_;
+		uint32_t time_;
 
 	};
 
diff --git a/thin_pool.cc b/thin_pool.cc
index c1fdc8d..0e5c9ce 100644
--- a/thin_pool.cc
+++ b/thin_pool.cc
@@ -109,6 +109,8 @@ thin_pool::create_thin(thin_dev_t dev)
 	single_mapping_tree::ptr new_tree(new single_mapping_tree(md_->tm_, block_time_ref_counter(md_->data_sm_)));
 	md_->mappings_top_level_.insert(key, new_tree->get_root());
 	md_->mappings_.set_root(md_->mappings_top_level_.get_root()); // FIXME: ugly
+
+	// FIXME: doesn't set up the device details
 }
 
 void
diff --git a/xml_format.cc b/xml_format.cc
index 0ef23ee..da938c2 100644
--- a/xml_format.cc
+++ b/xml_format.cc
@@ -83,20 +83,23 @@ namespace {
 			out_ << "<identifier name=\"" << name << "\"/>" << endl;
 		}
 
-		void range_map(uint64_t origin_begin, uint64_t data_begin, uint64_t len) {
+		void range_map(uint64_t origin_begin, uint64_t data_begin, uint32_t time, uint64_t len) {
 			indent();
 
 			out_ << "<range_mapping origin_begin=\"" << origin_begin << "\""
 			     << " data_begin=\"" << data_begin << "\""
-			     << " length=\"" << len << "\"/>"
-			     << endl;
+			     << " length=\"" << len << "\""
+			     << " time=\"" << time << "\""
+			     << "/>" << endl;
 		}
 
-		void single_map(uint64_t origin_block, uint64_t data_block) {
+		void single_map(uint64_t origin_block, uint64_t data_block, uint32_t time) {
 			indent();
 
 			out_ << "<single_mapping origin_block=\"" << origin_block << "\""
-			     << " data_block=\"" << data_block << "\"/>" << endl;
+			     << " data_block=\"" << data_block << "\""
+			     << " time=\"" << time << "\""
+			     << "/>" << endl;
 		}
 
 	private:
@@ -169,12 +172,14 @@ namespace {
 	void parse_range_mapping(emitter *e, attributes const &attr) {
 		e->range_map(get_attr<uint64_t>(attr, "origin_begin"),
 			     get_attr<uint64_t>(attr, "data_begin"),
+			     get_attr<uint32_t>(attr, "time"),
 			     get_attr<uint64_t>(attr, "length"));
 	}
 
 	void parse_single_mapping(emitter *e, attributes const &attr) {
 		e->single_map(get_attr<uint64_t>(attr, "origin_block"),
-			      get_attr<uint64_t>(attr, "data_block"));
+			      get_attr<uint64_t>(attr, "data_block"),
+			      get_attr<uint32_t>(attr, "time"));
 	}
 
 	void start_tag(void *data, char const *el, char const **attr) {