diff --git a/indexer/categories_holder.cpp b/indexer/categories_holder.cpp
index cac2e9e7fe..f677a57d92 100644
--- a/indexer/categories_holder.cpp
+++ b/indexer/categories_holder.cpp
@@ -27,7 +27,7 @@ int8_t const CategoriesHolder::kUnsupportedLocaleCode = -1;
 // translation to categories.txt. When editing, keep in mind to check
 // CategoriesHolder::MapLocaleToInteger() and
 // CategoriesHolder::MapIntegerToLocale() as their implementations
-// highly depend on the contents of the variable.
+// strongly depend on the contents of the variable.
 vector<CategoriesHolder::Mapping> const CategoriesHolder::kLocaleMapping = {{"en", 1},
                                                                             {"ru", 2},
                                                                             {"uk", 3},
diff --git a/indexer/categories_holder.hpp b/indexer/categories_holder.hpp
index 3719fd7fbc..948f58894c 100644
--- a/indexer/categories_holder.hpp
+++ b/indexer/categories_holder.hpp
@@ -6,6 +6,7 @@
 #include "std/shared_ptr.hpp"
 #include "std/string.hpp"
 #include "std/unique_ptr.hpp"
+#include "std/unordered_map.hpp"
 #include "std/vector.hpp"
 
 
@@ -129,7 +130,7 @@ public:
   }
 
   // Converts any language |locale| from UI to the corresponding
-  // internal integer code
+  // internal integer code.
   static int8_t MapLocaleToInteger(string const & locale);
 
   // Returns corresponding string representation for an internal
diff --git a/indexer/indexer_tests/categories_test.cpp b/indexer/indexer_tests/categories_test.cpp
index 141a05a152..8152110ca4 100644
--- a/indexer/indexer_tests/categories_test.cpp
+++ b/indexer/indexer_tests/categories_test.cpp
@@ -107,6 +107,18 @@ UNIT_TEST(LoadCategories)
   TEST_EQUAL(count, 3, ());
 }
 
+UNIT_TEST(CategoriesHolder_Smoke)
+{
+  auto const & mappings = CategoriesHolder::kLocaleMapping;
+  for (size_t i = 0; i < mappings.size(); ++i)
+  {
+    auto const & mapping  = mappings[i];
+    TEST_EQUAL(i + 1, mapping.m_code, ());
+    TEST_EQUAL(i + 1, CategoriesHolder::MapLocaleToInteger(mapping.m_name), ());
+    TEST_EQUAL(CategoriesHolder::MapIntegerToLocale(i + 1), mapping.m_name, ());
+  }
+}
+
 UNIT_TEST(CategoriesIndex_Smoke)
 {
   classificator::Load();
diff --git a/map/framework.hpp b/map/framework.hpp
index 50982d0f32..98774d76f3 100644
--- a/map/framework.hpp
+++ b/map/framework.hpp
@@ -120,8 +120,8 @@ protected:
 
   model::FeaturesFetcher m_model;
 
-  // The order matters here: DisplayedCategories may be used only when
-  // classificator is loaded (by |m_model|).
+  // The order matters here: DisplayedCategories may be used only
+  // after classificator is loaded by |m_model|.
   unique_ptr<search::DisplayedCategories> m_displayedCategories;
 
   // The order matters here: storage::CountryInfoGetter and
diff --git a/search/displayed_categories.hpp b/search/displayed_categories.hpp
index 781cb2a4d9..8f3cbd614c 100644
--- a/search/displayed_categories.hpp
+++ b/search/displayed_categories.hpp
@@ -18,6 +18,8 @@ public:
   // of resources ids.
   static vector<string> const & GetKeys();
 
+  // Calls |fn| on each pair (synonym name, synonym locale) for the
+  // |key|.
   template <typename Fn>
   void ForEachSynonym(string const & key, Fn && fn) const
   {