diff --git a/tests/models/test_tasklets.cpp b/tests/models/test_tasklets.cpp
index 922ae8c0f..3097c06e9 100644
--- a/tests/models/test_tasklets.cpp
+++ b/tests/models/test_tasklets.cpp
@@ -51,9 +51,8 @@ public:
     {
         assert(0 <= runner->workerThreadIndex() && runner->workerThreadIndex() < runner->numWorkerThreads());
         std::this_thread::sleep_for(std::chrono::milliseconds(mseconds_));
-        outputMutex.lock();
+        std::lock_guard<std::mutex> guard(outputMutex);
         std::cout << "Sleep tasklet " << n_ << " of " << mseconds_ << " ms completed by worker thread " << runner->workerThreadIndex() << std::endl;
-        outputMutex.unlock();
     }
 
 private:
@@ -67,9 +66,8 @@ void sleepAndPrintFunction()
 {
     int ms = 100;
     std::this_thread::sleep_for(std::chrono::milliseconds(ms));
-    outputMutex.lock();
+    std::lock_guard<std::mutex> guard(outputMutex);
     std::cout << "Sleep completed by worker thread " << runner->workerThreadIndex() << std::endl;
-    outputMutex.unlock();
 }
 
 int SleepTasklet::numInstantiated_ = 0;
diff --git a/tests/models/test_tasklets_failure.cpp b/tests/models/test_tasklets_failure.cpp
index 53d1efa05..01a891503 100644
--- a/tests/models/test_tasklets_failure.cpp
+++ b/tests/models/test_tasklets_failure.cpp
@@ -58,9 +58,8 @@ public:
         assert(0 <= runner->workerThreadIndex() && runner->workerThreadIndex() < runner->numWorkerThreads());
         std::cout << "Sleep tasklet " << id_ << " of " << mseconds_ << " ms starting sleep on worker thread " << runner->workerThreadIndex() << std::endl;
         std::this_thread::sleep_for(std::chrono::milliseconds(mseconds_));
-        outputMutex.lock();
+        std::lock_guard<std::mutex> guard(outputMutex);
         std::cout << "Sleep tasklet " << id_ << " of " << mseconds_ << " ms completed by worker thread " << runner->workerThreadIndex() << std::endl;
-        outputMutex.unlock();
     }
 
 private:
@@ -77,9 +76,8 @@ public:
     void run() override
     {
         std::this_thread::sleep_for(std::chrono::milliseconds(mseconds_));
-        outputMutex.lock();
+        std::lock_guard<std::mutex> guard(outputMutex);
         std::cout << "Failing sleep tasklet of " << mseconds_ << " ms failing now, on work thread " << runner->workerThreadIndex() << std::endl;
-        outputMutex.unlock();
         throw std::logic_error("Intentional failure for testing");
     }