diff --git a/persistent-data/space-maps/disk.cc b/persistent-data/space-maps/disk.cc
index 6cfd148..e641c89 100644
--- a/persistent-data/space-maps/disk.cc
+++ b/persistent-data/space-maps/disk.cc
@@ -646,6 +646,8 @@ namespace {
 		}
 
 		virtual void count_metadata(block_counter &bc) const {
+			bc.inc(bitmap_root_);
+
 			for (unsigned i = 0; i < entries_.size(); i++) {
 				block_address b = entries_[i].blocknr_;