diff --git a/Analyser/Dynamic/MultiMachine/Implementation/MultiCRTMachine.cpp b/Analyser/Dynamic/MultiMachine/Implementation/MultiCRTMachine.cpp
index 1da426514..b20a2c94e 100644
--- a/Analyser/Dynamic/MultiMachine/Implementation/MultiCRTMachine.cpp
+++ b/Analyser/Dynamic/MultiMachine/Implementation/MultiCRTMachine.cpp
@@ -34,17 +34,15 @@ void MultiCRTMachine::perform_parallel(const std::function<void(::CRTMachine::Ma
 			queues_[index].enqueue([&mutex, &condition, crt_machine, function, &outstanding_machines]() {
 				if(crt_machine) function(crt_machine);
 
-				{
-					std::lock_guard<std::mutex> lock(mutex);
-					outstanding_machines--;
-				}
+				std::lock_guard<std::mutex> lock(mutex);
+				outstanding_machines--;
 				condition.notify_all();
 			});
 		}
 	}
 
 	std::unique_lock<std::mutex> lock(mutex);
-	if(outstanding_machines) condition.wait(lock, [&outstanding_machines] { return !outstanding_machines; });
+	condition.wait(lock, [&outstanding_machines] { return !outstanding_machines; });
 }
 
 void MultiCRTMachine::perform_serial(const std::function<void (::CRTMachine::Machine *)> &function) {
@@ -100,7 +98,6 @@ bool MultiCRTMachine::get_clock_is_unlimited() {
 
 void MultiCRTMachine::did_change_machine_order() {
 	if(speaker_) {
-		std::lock_guard<std::mutex> machines_lock(machines_mutex_);
 		speaker_->set_new_front_machine(machines_.front().get());
 	}
 }
diff --git a/Analyser/Dynamic/MultiMachine/Implementation/MultiSpeaker.cpp b/Analyser/Dynamic/MultiMachine/Implementation/MultiSpeaker.cpp
index 1d1b741dd..47f92e305 100644
--- a/Analyser/Dynamic/MultiMachine/Implementation/MultiSpeaker.cpp
+++ b/Analyser/Dynamic/MultiMachine/Implementation/MultiSpeaker.cpp
@@ -48,11 +48,13 @@ void MultiSpeaker::set_delegate(Outputs::Speaker::Speaker::Delegate *delegate) {
 }
 
 void MultiSpeaker::speaker_did_complete_samples(Speaker *speaker, const std::vector<int16_t> &buffer) {
+	std::lock_guard<std::mutex> lock_guard(front_speaker_mutex_);
 	if(delegate_ && speaker == front_speaker_) {
 		delegate_->speaker_did_complete_samples(this, buffer);
 	}
 }
 
 void MultiSpeaker::set_new_front_machine(::Machine::DynamicMachine *machine) {
+	std::lock_guard<std::mutex> lock_guard(front_speaker_mutex_);
 	front_speaker_ = machine->crt_machine()->get_speaker();
 }
diff --git a/Analyser/Dynamic/MultiMachine/Implementation/MultiSpeaker.hpp b/Analyser/Dynamic/MultiMachine/Implementation/MultiSpeaker.hpp
index b5e9a28e9..84d2c910a 100644
--- a/Analyser/Dynamic/MultiMachine/Implementation/MultiSpeaker.hpp
+++ b/Analyser/Dynamic/MultiMachine/Implementation/MultiSpeaker.hpp
@@ -13,6 +13,7 @@
 #include "../../../../Outputs/Speaker/Speaker.hpp"
 
 #include <memory>
+#include <mutex>
 #include <vector>
 
 namespace Analyser {
@@ -34,6 +35,7 @@ class MultiSpeaker: public Outputs::Speaker::Speaker, Outputs::Speaker::Speaker:
 		std::vector<Outputs::Speaker::Speaker *> speakers_;
 		Outputs::Speaker::Speaker *front_speaker_ = nullptr;
 		Outputs::Speaker::Speaker::Delegate *delegate_ = nullptr;
+		std::mutex front_speaker_mutex_;
 };
 
 }
diff --git a/Analyser/Dynamic/MultiMachine/MultiMachine.cpp b/Analyser/Dynamic/MultiMachine/MultiMachine.cpp
index 608730e75..4927af57a 100644
--- a/Analyser/Dynamic/MultiMachine/MultiMachine.cpp
+++ b/Analyser/Dynamic/MultiMachine/MultiMachine.cpp
@@ -62,7 +62,6 @@ Configurable::Device *MultiMachine::configurable_device() {
 
 void MultiMachine::multi_crt_did_run_machines() {
 	std::lock_guard<std::mutex> machines_lock(machines_mutex_);
-	DynamicMachine *front = machines_.front().get();
 	for(const auto &machine: machines_) {
 		CRTMachine::Machine *crt = machine->crt_machine();
 		printf("%0.2f ", crt->get_confidence());
@@ -71,6 +70,7 @@ void MultiMachine::multi_crt_did_run_machines() {
 	}
 	printf("\n");
 
+	DynamicMachine *front = machines_.front().get();
 	std::stable_sort(machines_.begin(), machines_.end(), [] (const auto &lhs, const auto &rhs){
 		CRTMachine::Machine *lhs_crt = lhs->crt_machine();
 		CRTMachine::Machine *rhs_crt = rhs->crt_machine();