diff --git a/src/LRUCache.h b/src/LRUCache.h
index f101b3b..36f8064 100644
--- a/src/LRUCache.h
+++ b/src/LRUCache.h
@@ -6,13 +6,16 @@
 #include <list>
 #include <utility>
 #include <iostream>
+#include <memory>
+#include <mutex>
 
 template<class K, class V>
 class LRUCache {
-	using Key_list = std::list<std::pair<K, V>>;
+	using Key_list = std::list<std::pair<K, std::shared_ptr<V>>>;
 	Key_list key_values;
 	std::unordered_map<K, typename Key_list::iterator> positions;
 	size_t max_values;
+	std::mutex cache_mutex;
 
 	void remove_oldest() {
 		while (positions.size() >= max_values) {
@@ -25,17 +28,30 @@ public:
 	LRUCache(const size_t max_values) : max_values(max_values) {
 	}
 
-	template<class VV>
-	void insert(const K& key, VV&& value) {
+	void insert(const K& key, std::shared_ptr<V> value) {
+		std::lock_guard<std::mutex> lock(cache_mutex);
 		remove_oldest();
 		key_values.emplace_front(key, value);
 		positions[key] = key_values.begin();
 	}
 
-	std::pair<V*, bool> find(const K& key) {
+	void insert(const K& key, V* value) {
+		insert(key, std::shared_ptr<V>(value));
+	}
+
+	void insert(const K& key, V&& value) {
+		insert(key, std::make_shared<V>(std::move(value)));
+	}
+
+	void insert(const K& key, V& value) {
+		insert(key, std::make_shared<V>(value));
+	}
+
+	std::shared_ptr<V> find(const K& key) {
+		std::lock_guard<std::mutex> lock(cache_mutex);
 		auto p = positions.find(key);
 		if (p == positions.end())
-			return {nullptr, false};
+			return {};
 		auto iter = p->second;
 		auto& value = iter->second;
 		// If the iterator is not at the front of the list, move it there.
@@ -47,12 +63,13 @@ public:
 					std::next(iter));
 		}
 		positions[key] = key_values.begin();
-		return {&(iter->second), true};
+		return iter->second;
 	}
 
 	void debug_cache() {
+		std::lock_guard<std::mutex> lock(cache_mutex);
 		for (auto& p : key_values) {
-			std::cout << p.first << ":" << p.second << std::endl;
+			std::cout << p.first << ":" << *p.second << std::endl;
 		}
 	}
 };
diff --git a/tests/LRUCache-test.cpp b/tests/LRUCache-test.cpp
index d6cc95a..beed296 100644
--- a/tests/LRUCache-test.cpp
+++ b/tests/LRUCache-test.cpp
@@ -7,7 +7,7 @@ using namespace std;
 int main(int argc, char **argv) {
 	LRUCache<string, int> lru(4);
 
-	lru.insert("hello", 1);
+	lru.insert("hello", new int(1));
 	lru.insert("hi", 2);
 	lru.insert("where", 3);
 	lru.insert("are", 4);