diff --git lib-src/PlainHashIndexTable.hh lib-src/PlainHashIndexTable.hh
index 068460d..9dff216 100644
--- lib-src/PlainHashIndexTable.hh
+++ lib-src/PlainHashIndexTable.hh
@@ -15,8 +15,8 @@
 
 #include <vector>
 
-#include <mutex>
-#include <shared_mutex>
+#include <boost/thread/mutex.hpp>
+#include <boost/thread/shared_mutex.hpp>
 #include <atomic>
 
 #include "Global.hh"
@@ -55,7 +55,7 @@ namespace topcom {
     index_table_type          _index_data;
     mutable bool              _preprocessed;
     mutable bool              _inside_multithreading;
-    mutable std::shared_mutex _index_data_mutex; 
+    mutable boost::shared_mutex _index_data_mutex;
   public:
     // constructors:
     inline PlainHashIndexTable(const bool inside_multithreading = false) :
@@ -91,7 +91,7 @@ namespace topcom {
 	_preprocessed = phit._preprocessed;
       }
       else {
-	std::unique_lock<std::shared_mutex> _index_data_guard(_index_data_mutex);
+	std::unique_lock<boost::shared_mutex> _index_data_guard(_index_data_mutex);
 	key_table_type::operator=(phit);
 	_index_data = phit._index_data;
 	_preprocessed = phit._preprocessed;
@@ -117,8 +117,8 @@ namespace topcom {
 	return _index_data[index];
       }
       else {
-	// std::unique_lock<std::shared_mutex> _index_data_guard(_index_data_mutex);
-	std::shared_lock<std::shared_mutex> _index_data_guard(_index_data_mutex);
+	// std::unique_lock<boost::shared_mutex> _index_data_guard(_index_data_mutex);
+	boost::shared_lock<boost::shared_mutex> _index_data_guard(_index_data_mutex);
 	return _index_data[index];
       }
     }
@@ -142,7 +142,7 @@ namespace topcom {
 	if (_inside_multithreading) {
 	  {
 	    // std::lock_guard<std::mutex> _index_data_guard(_index_data_mutex);
-	    std::unique_lock<std::shared_mutex> _index_data_guard(_index_data_mutex);
+	    std::unique_lock<boost::shared_mutex> _index_data_guard(_index_data_mutex);
 	    auto finder(key_table_type::find(key));
 	    if (finder != key_table_type::end()) {
 	      return finder->second;
@@ -150,7 +150,7 @@ namespace topcom {
 	  }
 	  // write access from here - guard:
 	  // std::lock_guard<std::mutex> _index_data_guard(_index_data_mutex);
-	  std::unique_lock<std::shared_mutex> _index_data_guard(_index_data_mutex);
+	  std::unique_lock<boost::shared_mutex> _index_data_guard(_index_data_mutex);
 	  const size_type new_index(_index_data.size());
 	  key_table_type::insert(std::pair<Key, size_type>(key, new_index));
 	  // _index_data.resize(new_index + 1);