diff --git a/src/Gui/CommandTest.cpp b/src/Gui/CommandTest.cpp
index 3f4cc9b1e6af..243eac15eb30 100644
--- a/src/Gui/CommandTest.cpp
+++ b/src/Gui/CommandTest.cpp
@@ -27,6 +27,7 @@
 # include <QEventLoop>
 # include <QFileDialog>
 # include <QMutex>
+# include <QMutexLocker>
 # include <QThread>
 # include <QTimer>
 # include <QMdiArea>
@@ -294,10 +295,10 @@ CmdTestProgress1::CmdTestProgress1()
 
 void CmdTestProgress1::activated(int iMsg)
 {
+    QMutex mutex;
+    QMutexLocker ml(&mutex);
     try
     {
-        QMutex mutex;
-        mutex.lock();
         unsigned long steps = 1000;
         Base::SequencerLauncher seq("Starting progress bar", steps);
 
@@ -306,8 +307,6 @@ void CmdTestProgress1::activated(int iMsg)
             seq.next(true);
             QWaitCondition().wait(&mutex, 30);
         }
-
-        mutex.unlock();
     }
     catch (...)
     {
@@ -337,10 +336,11 @@ CmdTestProgress2::CmdTestProgress2()
 
 void CmdTestProgress2::activated(int iMsg)
 {
+    QMutex mutex;
+    QMutexLocker ml(&mutex);
+
     try
     {
-        QMutex mutex;
-        mutex.lock();
         unsigned long steps = 1000;
         Base::SequencerLauncher seq("Starting progress bar", steps);
 
@@ -378,11 +378,12 @@ CmdTestProgress3::CmdTestProgress3()
 
 void CmdTestProgress3::activated(int iMsg)
 {
+    QMutex mutex;
+    QMutexLocker ml(&mutex);
+    
     try
     {
         // level 1
-        QMutex mutex;
-        mutex.lock();
         unsigned long steps = 5;
         Base::SequencerLauncher seq1("Starting progress bar", steps);
         for (unsigned long i=0; i<steps;i++)
@@ -446,10 +447,11 @@ CmdTestProgress4::CmdTestProgress4()
 
 void CmdTestProgress4::activated(int iMsg)
 {
+    QMutex mutex;
+    QMutexLocker ml(&mutex);
+
     try
     {
-        QMutex mutex;
-        mutex.lock();
         unsigned long steps = 50;
         Base::SequencerLauncher* seq = new Base::SequencerLauncher("Starting progress bar", steps);
 
@@ -508,10 +510,11 @@ class BarThread : public QThread
     }
     void run()
     {
+        QMutex mutex;
+        QMutexLocker ml(&mutex);
+	
         try
         {
-            QMutex mutex;
-            mutex.lock();
             Base::SequencerLauncher seq("Starting progress bar in thread", steps);
 
             for (unsigned long i=0; i<this->steps;i++)
@@ -519,7 +522,6 @@ class BarThread : public QThread
                 seq.next(true);
                 QWaitCondition().wait(&mutex, 5);
             }
-            mutex.unlock();
         }
         catch (...)
         {
@@ -662,27 +664,23 @@ class TestConsoleObserver : public Base::ConsoleObserver
     }
     virtual void Warning(const char * msg)
     {
-        mutex.lock();
+        QMutexLocker ml(&mutex);
         matchWrn += strcmp(msg, "Write a warning to the console output.\n");
-        mutex.unlock();
     }
     virtual void Message(const char * msg)
     {
-        mutex.lock();
+        QMutexLocker ml(&mutex);
         matchMsg += strcmp(msg, "Write a message to the console output.\n");
-        mutex.unlock();
     }
     virtual void Error(const char * msg)
     {
-        mutex.lock();
+        QMutexLocker ml(&mutex);
         matchErr += strcmp(msg, "Write an error to the console output.\n");
-        mutex.unlock();
     }
     virtual void Log(const char * msg)
     {
-        mutex.lock();
+        QMutexLocker ml(&mutex);
         matchLog += strcmp(msg, "Write a log to the console output.\n");
-        mutex.unlock();
     }
 };
 
diff --git a/src/Gui/Quarter/SignalThread.cpp b/src/Gui/Quarter/SignalThread.cpp
index bcd9b78c6ee4..2b7254d3ceaa 100644
--- a/src/Gui/Quarter/SignalThread.cpp
+++ b/src/Gui/Quarter/SignalThread.cpp
@@ -30,6 +30,8 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 \**************************************************************************/
 
+#include <QMutexLocker>
+
 #include "SignalThread.h"
 
 using namespace SIM::Coin3D::Quarter;
@@ -47,25 +49,23 @@ void
 SignalThread::trigger(void)
 {
   // lock first to make sure the QThread is actually waiting for a signal
-  this->mutex.lock();
+  QMutexLocker ml(&this->mutex);
   this->waitcond.wakeOne();
-  this->mutex.unlock();
 }
 
 void
 SignalThread::stopThread(void)
 {
-  this->mutex.lock();
+  QMutexLocker ml(&this->mutex);
   this->isstopped = true;
   this->waitcond.wakeOne();
-  this->mutex.unlock();
 }
 
 
 void
 SignalThread::run(void)
 {
-  this->mutex.lock();
+  QMutexLocker ml(&this->mutex);
   while (!this->isstopped) {
     // just wait, and trigger every time we receive a signal
     this->waitcond.wait(&this->mutex);
@@ -73,5 +73,4 @@ SignalThread::run(void)
       emit triggerSignal();
     }
   }
-  this->mutex.unlock();
 }
diff --git a/src/Gui/Splashscreen.cpp b/src/Gui/Splashscreen.cpp
index a200776204c6..0e6610abefa2 100644
--- a/src/Gui/Splashscreen.cpp
+++ b/src/Gui/Splashscreen.cpp
@@ -134,7 +134,7 @@ class SplashObserver : public Base::ConsoleObserver
 
         splash->showMessage(msg.replace(QLatin1String("\n"), QString()), alignment, textColor);
         QMutex mutex;
-        mutex.lock();
+        QMutexLocker ml(&mutex);
         QWaitCondition().wait(&mutex, 50);
     }