diff --git a/storage/storage_tests/simple_tree_test.cpp b/storage/storage_tests/simple_tree_test.cpp
index e47ad8c4b1..eb75243847 100644
--- a/storage/storage_tests/simple_tree_test.cpp
+++ b/storage/storage_tests/simple_tree_test.cpp
@@ -2,17 +2,6 @@
 
 #include "storage/country_tree.hpp"
 
-namespace
-{
-template <class Node>
-struct Calculator
-{
-  size_t count;
-  Calculator() : count(0) {}
-  void operator()(Node const &) { ++count; }
-};
-} // namespace
-
 UNIT_TEST(CountryTree_Smoke)
 {
   using Tree = storage::CountryTree::Node;
@@ -45,15 +34,16 @@ UNIT_TEST(CountryTree_Smoke)
   TEST_EQUAL(tree.Child(4).Child(0).Parent().Value().Name(), "1", ());
   TEST_EQUAL(tree.Child(4).Child(2).Parent().Value().Name(), "1", ());
 
-  Calculator<Tree> c1;
-  tree.ForEachChild(c1);
-  TEST_EQUAL(c1.count, 5, ());
+  size_t count = 0;
+  auto countCallback = [&count](Tree const &) { ++count; };
+  tree.ForEachChild(countCallback);
+  TEST_EQUAL(count, 5, ());
 
-  Calculator<Tree> c2;
-  tree.ForEachDescendant(c2);
-  TEST_EQUAL(c2.count, 8, ());
+  count = 0;
+  tree.ForEachDescendant(countCallback);
+  TEST_EQUAL(count, 8, ());
 
-  Calculator<Tree> c3;
-  tree.Child(4).Child(0).ForEachAncestorExceptForTheRoot(c3);
-  TEST_EQUAL(c3.count, 1, ());
+  count = 0;
+  tree.Child(4).Child(0).ForEachAncestorExceptForTheRoot(countCallback);
+  TEST_EQUAL(count, 1, ());
 }