diff --git a/unit-tests/btree_counter_t.cc b/unit-tests/btree_counter_t.cc
index 39412c7..0aa01c0 100644
--- a/unit-tests/btree_counter_t.cc
+++ b/unit-tests/btree_counter_t.cc
@@ -28,11 +28,21 @@ namespace {
 			  tm_(bm_, sm_) {
 		}
 
-		void check_nr_metadata_blocks_is_ge(unsigned n) {
-			block_counter bc;
+		size_t get_nr_metadata_blocks(bool ignore_non_fatal = false,
+					      bool stop_on_error = false) {
+			block_counter bc(stop_on_error);
 			noop_value_counter<uint64_t> vc;
-			count_btree_blocks(*tree_, bc, vc);
-			ASSERT_THAT(bc.get_counts().size(), Ge(n));
+			count_btree_blocks(*tree_, bc, vc, ignore_non_fatal);
+			return bc.get_counts().size();
+		}
+
+		void damage_first_leaf_underfull() {
+			bcache::validator::ptr v = create_btree_node_validator();
+
+			block_address b = get_first_leaf();
+			block_manager::write_ref blk = bm_->write_lock(b, v);
+			btree<1, uint64_traits>::leaf_node n = to_node<uint64_traits>(blk);
+			n.set_nr_entries(1);
 		}
 
 		with_temp_directory dir_;
@@ -53,6 +63,19 @@ namespace {
 		void commit() {
 			block_manager::write_ref superblock(bm_->superblock(SUPERBLOCK));
 		}
+
+		block_address get_first_leaf() {
+			bcache::validator::ptr v = create_btree_node_validator();
+
+			block_manager::read_ref root = bm_->read_lock(tree_->get_root(), v);
+			btree<1, uint64_traits>::internal_node n = to_node<block_traits>(root);
+			while (n.get_type() == INTERNAL) {
+				block_manager::read_ref internal = bm_->read_lock(n.value_at(0), v);
+				n = to_node<block_traits>(internal);
+			}
+
+			return n.get_block_nr();
+		}
 	};
 }
 
@@ -62,7 +85,7 @@ TEST_F(BTreeCounterTests, count_empty_tree)
 {
 	tree_.reset(new btree<1, uint64_traits>(tm_, rc_));
 	tm_.get_bm()->flush();
-	check_nr_metadata_blocks_is_ge(1);
+	ASSERT_GE(get_nr_metadata_blocks(), 1u);
 }
 
 TEST_F(BTreeCounterTests, count_populated_tree)
@@ -75,7 +98,44 @@ TEST_F(BTreeCounterTests, count_populated_tree)
 	}
 
 	tm_.get_bm()->flush();
-	check_nr_metadata_blocks_is_ge(40);
+	ASSERT_GE(get_nr_metadata_blocks(), 40u);
+}
+
+TEST_F(BTreeCounterTests, count_underfull_nodes)
+{
+	tree_.reset(new btree<1, uint64_traits>(tm_, rc_));
+
+	for (unsigned i = 0; i < 10000; i++) {
+		uint64_t key[1] = {i};
+		tree_->insert(key, 0ull);
+	}
+
+	tm_.get_bm()->flush();
+	size_t nr_blocks = get_nr_metadata_blocks();
+
+	damage_first_leaf_underfull();
+	tm_.get_bm()->flush();
+
+	// underfull nodes are not counted
+	bool ignore_non_fatal = false;
+	bool stop_on_error = false;
+	ASSERT_EQ(get_nr_metadata_blocks(ignore_non_fatal, stop_on_error), nr_blocks - 1);
+
+	// underfull nodes are counted
+	ignore_non_fatal = true;
+	stop_on_error = false;
+	ASSERT_EQ(get_nr_metadata_blocks(ignore_non_fatal, stop_on_error), nr_blocks);
+
+	// logical errors like underfull nodes don't result in exceptions,
+	// therefore the stop_on_error flag has no effect.
+	// FIXME: is it necessary to stop the counting on logical errors?
+	ignore_non_fatal = false;
+	stop_on_error = true;
+	ASSERT_EQ(get_nr_metadata_blocks(ignore_non_fatal, stop_on_error), nr_blocks - 1);
+
+	ignore_non_fatal = true;
+	stop_on_error = true;
+	ASSERT_EQ(get_nr_metadata_blocks(ignore_non_fatal, stop_on_error), nr_blocks);
 }
 
 //----------------------------------------------------------------