diff --git a/persistent-data/data-structures/btree_node_checker.cc b/persistent-data/data-structures/btree_node_checker.cc
index a6c77e0..0f50670 100644
--- a/persistent-data/data-structures/btree_node_checker.cc
+++ b/persistent-data/data-structures/btree_node_checker.cc
@@ -6,11 +6,11 @@ using persistent_data::btree_detail::btree_node_checker;
 
 //----------------------------------------------------------------
 
-btree_node_checker::error_type btree_node_checker::get_last_error() {
+btree_node_checker::error_type btree_node_checker::get_last_error() const {
 	return last_error_;
 }
 
-std::string btree_node_checker::get_last_error_string() {
+std::string btree_node_checker::get_last_error_string() const {
 	switch (last_error_) {
 	case BLOCK_NR_MISMATCH:
 		return block_nr_mismatch_string();
@@ -39,7 +39,7 @@ void btree_node_checker::reset() {
 	last_error_ = NO_ERROR;
 }
 
-std::string btree_node_checker::block_nr_mismatch_string() {
+std::string btree_node_checker::block_nr_mismatch_string() const {
 	std::ostringstream out;
 	out << "block number mismatch: actually "
 	    << error_location_
@@ -48,7 +48,7 @@ std::string btree_node_checker::block_nr_mismatch_string() {
 	return out.str();
 }
 
-std::string btree_node_checker::value_sizes_mismatch_string() {
+std::string btree_node_checker::value_sizes_mismatch_string() const {
 	std::ostringstream out;
 	out << "value size mismatch: expected " << error_value_sizes_[1]
 	    << ", but got " << error_value_sizes_[0]
@@ -58,7 +58,7 @@ std::string btree_node_checker::value_sizes_mismatch_string() {
 	return out.str();
 }
 
-std::string btree_node_checker::max_entries_too_large_string() {
+std::string btree_node_checker::max_entries_too_large_string() const {
 	std::ostringstream out;
 	out << "max entries too large: " << error_max_entries_
 	    << " (block " << error_location_ << ")";
@@ -66,7 +66,7 @@ std::string btree_node_checker::max_entries_too_large_string() {
 	return out.str();
 }
 
-std::string btree_node_checker::max_entries_not_divisible_string() {
+std::string btree_node_checker::max_entries_not_divisible_string() const {
 	std::ostringstream out;
 	out << "max entries is not divisible by 3: " << error_max_entries_
 	    << " (block " << error_location_ << ")";
@@ -74,7 +74,7 @@ std::string btree_node_checker::max_entries_not_divisible_string() {
 	return out.str();
 }
 
-std::string btree_node_checker::nr_entries_too_large_string() {
+std::string btree_node_checker::nr_entries_too_large_string() const {
 	std::ostringstream out;
 	out << "bad nr_entries: "
 	    << error_nr_entries_ << " < "
@@ -84,7 +84,7 @@ std::string btree_node_checker::nr_entries_too_large_string() {
 	return out.str();
 }
 
-std::string btree_node_checker::nr_entries_too_small_string() {
+std::string btree_node_checker::nr_entries_too_small_string() const {
 	std::ostringstream out;
 	out << "too few entries in btree_node: "
 	    << error_nr_entries_
@@ -96,7 +96,7 @@ std::string btree_node_checker::nr_entries_too_small_string() {
 	return out.str();
 }
 
-std::string btree_node_checker::keys_out_of_order_string() {
+std::string btree_node_checker::keys_out_of_order_string() const {
 	std::ostringstream out;
 	out << "keys are out of order, "
 	    << error_keys_[0] << " <= " << error_keys_[1]
@@ -105,7 +105,7 @@ std::string btree_node_checker::keys_out_of_order_string() {
 	return out.str();
 }
 
-std::string btree_node_checker::parent_key_mismatch_string() {
+std::string btree_node_checker::parent_key_mismatch_string() const {
 	std::ostringstream out;
 	out << "parent key mismatch: parent was " << error_keys_[1]
 	    << ", but lowest in node was " << error_keys_[0]
@@ -114,7 +114,7 @@ std::string btree_node_checker::parent_key_mismatch_string() {
 	return out.str();
 }
 
-std::string btree_node_checker::leaf_key_overlapped_string() {
+std::string btree_node_checker::leaf_key_overlapped_string() const {
 	std::ostringstream out;
 	out << "the last key of the previous leaf was " << error_keys_[1]
 	    << " and the first key of this leaf is " << error_keys_[0]
diff --git a/persistent-data/data-structures/btree_node_checker.h b/persistent-data/data-structures/btree_node_checker.h
index 926f613..be50007 100644
--- a/persistent-data/data-structures/btree_node_checker.h
+++ b/persistent-data/data-structures/btree_node_checker.h
@@ -41,6 +41,8 @@ namespace persistent_data {
 				error_keys_{0, 0} {
 			}
 
+			virtual ~btree_node_checker() {}
+
 			template <typename ValueTraits>
 			bool check_block_nr(btree_detail::node_ref<ValueTraits> const &n) {
 				if (n.get_location() != n.get_block_nr()) {
@@ -175,20 +177,20 @@ namespace persistent_data {
 				return true;
 			}
 
-			error_type get_last_error();
-			std::string get_last_error_string();
+			error_type get_last_error() const;
+			std::string get_last_error_string() const;
 			void reset();
 
 		private:
-			std::string block_nr_mismatch_string();
-			std::string value_sizes_mismatch_string();
-			std::string max_entries_too_large_string();
-			std::string max_entries_not_divisible_string();
-			std::string nr_entries_too_large_string();
-			std::string nr_entries_too_small_string();
-			std::string keys_out_of_order_string();
-			std::string parent_key_mismatch_string();
-			std::string leaf_key_overlapped_string();
+			std::string block_nr_mismatch_string() const;
+			std::string value_sizes_mismatch_string() const;
+			std::string max_entries_too_large_string() const;
+			std::string max_entries_not_divisible_string() const;
+			std::string nr_entries_too_large_string() const;
+			std::string nr_entries_too_small_string() const;
+			std::string keys_out_of_order_string() const;
+			std::string parent_key_mismatch_string() const;
+			std::string leaf_key_overlapped_string() const;
 
 			error_type last_error_;
 			block_address error_location_;
diff --git a/thin-provisioning/thin_ll_dump.cc b/thin-provisioning/thin_ll_dump.cc
index f16a745..94f6a08 100644
--- a/thin-provisioning/thin_ll_dump.cc
+++ b/thin-provisioning/thin_ll_dump.cc
@@ -330,7 +330,7 @@ thin_ll_dump_cmd::run(int argc, char **argv)
 	boost::optional<string> output;
 	flags f;
 
-	char c;
+	int c;
 	while ((c = getopt_long(argc, argv, shortopts, longopts, NULL)) != -1) {
 		switch(c) {
 		case 'h':
diff --git a/thin-provisioning/thin_ll_restore.cc b/thin-provisioning/thin_ll_restore.cc
index 27ab184..4082e0b 100644
--- a/thin-provisioning/thin_ll_restore.cc
+++ b/thin-provisioning/thin_ll_restore.cc
@@ -87,7 +87,7 @@ namespace {
 		device_tree_detail::device_details details;
 
 		device_tree::ptr details_tree;
-		boost::optional<uint32_t> details_root = get_opt_attr<uint32_t>(attr, "blocknr");
+		boost::optional<uint64_t> details_root = get_opt_attr<uint64_t>(attr, "blocknr");
 		if (details_root)
 			details_tree = device_tree::ptr(new device_tree(*md->tm_, *details_root,
 							device_tree_detail::device_details_traits::ref_counter()));
@@ -112,7 +112,7 @@ namespace {
 	}
 
 	void parse_node(metadata::ptr md, emitter::ptr e, attributes const &attr) {
-		metadata_dump_subtree(md, e, true, get_attr<uint32_t>(attr, "blocknr"));
+		metadata_dump_subtree(md, e, true, get_attr<uint64_t>(attr, "blocknr"));
 	}
 
 	void start_tag(void *data, char const *el, char const **attr) {
@@ -216,7 +216,7 @@ thin_ll_restore_cmd::run(int argc, char **argv) {
 	string output;
 	string input_metadata;
 	flags f;
-	char c;
+	int c;
 
 	const char shortopts[] = "hi:o:E:V";
 	const struct option longopts[] = {
diff --git a/thin-provisioning/thin_scan.cc b/thin-provisioning/thin_scan.cc
index 1ed7a6b..6f63df0 100644
--- a/thin-provisioning/thin_scan.cc
+++ b/thin-provisioning/thin_scan.cc
@@ -383,7 +383,7 @@ thin_scan_cmd::run(int argc, char **argv)
 	boost::optional<string> output;
 	flags f;
 
-	char c;
+	int c;
 	while ((c = getopt_long(argc, argv, shortopts, longopts, NULL)) != -1) {
 		switch(c) {
 		case 'h':