diff --git a/src/message/migfra/task.cpp b/src/message/migfra/task.cpp
index 7d8584e..93f7eed 100644
--- a/src/message/migfra/task.cpp
+++ b/src/message/migfra/task.cpp
@@ -176,7 +176,7 @@ void Task_container::load(const YAML::Node &node)
 	std::string type;
 	try {
 		fast::load(type, node["task"]);
-	} catch (const std::exception /*&e*/) {
+	} catch (const std::exception &/*e*/) {
 		throw Task_container::no_task_exception("Cannot find key \"task\" to load Task from YAML.");
 	}
 	if (type == "start vm") {
diff --git a/src/mqtt_communicator.cpp b/src/mqtt_communicator.cpp
index b62b790..b273b6b 100644
--- a/src/mqtt_communicator.cpp
+++ b/src/mqtt_communicator.cpp
@@ -328,7 +328,7 @@ std::string MQTT_communicator::get_message(const std::string &topic, const std::
 		auto &subscription = subscriptions.at(topic);
 		lock.unlock();
 		return subscription->get_message(duration, actual_topic);
-	} catch (const std::out_of_range /*&e*/) {
+	} catch (const std::out_of_range &/*e*/) {
 		throw std::out_of_range("Topic not found in subscriptions.");
 	}
 }
diff --git a/test/optional_test.cpp b/test/optional_test.cpp
index 917a894..b463541 100644
--- a/test/optional_test.cpp
+++ b/test/optional_test.cpp
@@ -58,15 +58,15 @@ struct Task_tester :
 		fructose_assert_eq(tag, p.get_tag());
 		fructose_assert_exception(p.get(), std::runtime_error);
 		fructose_assert_exception(*p, std::runtime_error);
-		fructose_assert_exception(p->id, std::runtime_error);
+		fructose_assert_exception((void) p->id, std::runtime_error);
 		p = Person(1);
 		fructose_assert(p);
 		fructose_assert(p.is_valid());
 		fructose_assert_no_exception(p.get());
 		fructose_assert_no_exception(*p);
-		fructose_assert_no_exception((*p).id);
-		fructose_assert_no_exception(p.get().id);
-		fructose_assert_no_exception(p->id);
+		fructose_assert_no_exception((void) (*p).id);
+		fructose_assert_no_exception((void) p.get().id);
+		fructose_assert_no_exception((void) p->id);
 		fructose_assert((*p).id == 1);
 		fructose_assert(p.get().id == 1);
 		fructose_assert(p->id == 1);