diff --git a/README b/README
index e69de29..615274c 100644
--- a/README
+++ b/README
@@ -0,0 +1 @@
+The examples show how to get distribution of feature types from GFF3 file with Intel Threading Building Blocks, using parallel_for or parallel_pipeline constructs and lambda functions from C++11.
diff --git a/src/types2.cpp b/src/types2.cpp
index 586fa91..8d89fb7 100644
--- a/src/types2.cpp
+++ b/src/types2.cpp
@@ -19,7 +19,7 @@ int main(int argc, const char** argv) {
 
     ifstream fin("../data/Cucumber_v2i.gff3");
     
-    unordered_map<string, unsigned int> occurrences;
+    tbb::concurrent_unordered_map<string, unsigned int> occurrences;
     
     const size_t CHUNK_SIZE = argc == 1 ? 100 : atoi(argv[1]);