diff --git a/fortuna.cpp b/fortuna.cpp
index 62751f9..1d3e351 100644
--- a/fortuna.cpp
+++ b/fortuna.cpp
@@ -55,6 +55,8 @@ Fortuna::~Fortuna() noexcept {
 
 
 auto Fortuna::random_data(unsigned int n_bytes) -> void {
+	std::lock_guard<std::mutex> lg(mtx_random_data);
+
 	const auto start{std::chrono::system_clock::now()};
 	fmt::print("random_data starting - {}\n", start);
 	auto elapsed{std::chrono::duration_cast<std::chrono::milliseconds>(
diff --git a/fortuna.h b/fortuna.h
index acd5b41..6a62dc3 100644
--- a/fortuna.h
+++ b/fortuna.h
@@ -19,6 +19,7 @@ class Fortuna {
 public:
 	static constexpr const char NUM_OF_POOLS{32};
 	std::mutex mtx;
+	std::mutex mtx_random_data;
 	std::mutex accu_mtx;
 	std::mutex print_mtx;
 	std::thread th_gen;