diff --git a/fortuna.cpp b/fortuna.cpp
index 01a41c4..498c239 100644
--- a/fortuna.cpp
+++ b/fortuna.cpp
@@ -42,7 +42,7 @@ auto Fortuna::random_data(unsigned int n_bytes) -> void {
 	std::string s;
 	// synchronise reads and writes to the between
 	// {generator,accumulator,fortuna} service threads
-	std::lock_guard<std::mutex> lg(mtx);
+	std::unique_lock<std::mutex> uq_lock(mtx);
 	const int pools_to_use{ffsll(static_cast<int>(get_reseed_ctr()))};
 
 	if (R.pools[0].get_s_length() >= min_pool_size && elapsed > R.Gen.reseed_interval) {
@@ -71,6 +71,7 @@ auto Fortuna::random_data(unsigned int n_bytes) -> void {
 				n_bytes, n);
 		n.clear();
 	}
+	uq_lock.unlock();
 
 	const auto end{std::chrono::system_clock::now()};
 	std::chrono::duration<float> diff = end-start;