diff --git a/persistent-data/space_map_core.h b/persistent-data/space_map_core.h
index 05e8c32..700b8e6 100644
--- a/persistent-data/space_map_core.h
+++ b/persistent-data/space_map_core.h
@@ -24,8 +24,10 @@
 //----------------------------------------------------------------
 
 namespace persistent_data {
-	class core_map : public space_map {
+	class core_map : public checked_space_map {
 	public:
+		typedef boost::shared_ptr<core_map> ptr;
+
 		core_map(block_address nr_blocks)
 			: counts_(nr_blocks, 0),
 			  nr_free_(nr_blocks) {
@@ -93,6 +95,20 @@ namespace persistent_data {
 			throw std::runtime_error("not implemented");
 		}
 
+		// FIXME: meaningless, but this class is only used for testing
+		size_t root_size() const {
+			return 0;
+		}
+
+		// FIXME: meaningless, but this class is only used for testing
+		virtual void copy_root(void *dest, size_t len) const {
+			throw std::runtime_error("not implemented");
+		}
+
+		checked_space_map::ptr clone() const {
+			return ptr(new core_map(*this));
+		}
+
 	private:
 		std::vector<ref_t> counts_;
 		unsigned nr_free_;
diff --git a/persistent-data/space_map_transactional.h b/persistent-data/space_map_transactional.h
index 635059d..cec8c97 100644
--- a/persistent-data/space_map_transactional.h
+++ b/persistent-data/space_map_transactional.h
@@ -24,7 +24,7 @@
 //----------------------------------------------------------------
 
 namespace persistent_data {
-	
+
 	// FIXME: change name 'transactional' is so vague.
 
 	// This space map ensures no blocks are allocated which have been
diff --git a/unit-tests/space_map_t.cc b/unit-tests/space_map_t.cc
index fce97f6..d663128 100644
--- a/unit-tests/space_map_t.cc
+++ b/unit-tests/space_map_t.cc
@@ -18,6 +18,7 @@
 
 #include "persistent-data/space_map_disk.h"
 #include "persistent-data/space_map_core.h"
+#include "persistent-data/space_map_transactional.h"
 
 #define BOOST_TEST_MODULE SpaceMapDiskTests
 #include <boost/test/included/unit_test.hpp>
@@ -37,7 +38,7 @@ namespace {
 	create_tm() {
 		block_manager<>::ptr bm(
 			new block_manager<>("./test.data", NR_BLOCKS, MAX_LOCKS, true));
-		space_map::ptr sm(new core_map(1024));
+		space_map::ptr sm(new core_map(NR_BLOCKS));
 		transaction_manager::ptr tm(
 			new transaction_manager(bm, sm));
 		return tm;
@@ -51,6 +52,16 @@ namespace {
 		}
 	};
 
+	class sm_transactional_creator {
+	public:
+		static space_map::ptr
+		create() {
+			return create_transactional_sm(
+				checked_space_map::ptr(
+					new core_map(NR_BLOCKS)));
+		}
+	};
+
 	class sm_disk_creator {
 	public:
 		static persistent_space_map::ptr
@@ -248,6 +259,11 @@ BOOST_AUTO_TEST_CASE(test_sm_core)
 	do_tests<sm_core_creator>(space_map_tests);
 }
 
+BOOST_AUTO_TEST_CASE(test_sm_transactional)
+{
+	do_tests<sm_transactional_creator>(space_map_tests);
+}
+
 BOOST_AUTO_TEST_CASE(test_sm_disk)
 {
 	do_tests<sm_disk_creator>(space_map_tests);