diff --git a/persistent-data/buffer.h b/persistent-data/buffer.h
index d9a7e07..45e2390 100644
--- a/persistent-data/buffer.h
+++ b/persistent-data/buffer.h
@@ -44,6 +44,7 @@ namespace persistent_data {
 	class buffer : private boost::noncopyable {
 	public:
 		typedef boost::shared_ptr<buffer> ptr;
+		typedef boost::shared_ptr<buffer const> const_ptr;
 
 		unsigned char &operator[](unsigned index) {
 			check_index(index);
diff --git a/unit-tests/buffer_t.cc b/unit-tests/buffer_t.cc
index 248ad0a..69ea853 100644
--- a/unit-tests/buffer_t.cc
+++ b/unit-tests/buffer_t.cc
@@ -85,7 +85,7 @@ BOOST_AUTO_TEST_CASE(buffer_8_a_8_access)
 BOOST_AUTO_TEST_CASE(buffer_8_a_8_const_access)
 {
 	uint32_t const sz = 8, align = 8;
-	buffer<sz, align>::ptr const b = create_buffer<sz, align>();
+	buffer<sz, align>::const_ptr b = create_buffer<sz, align>();
 
 	(*b)[0] = 0; // Compile time error accessing read-only location 
 }