diff --git a/src/core/atcore.h b/src/core/atcore.h
--- a/src/core/atcore.h
+++ b/src/core/atcore.h
@@ -267,7 +267,7 @@
      * @param newProgress : Message
      * @sa percentagePrinted()
      */
-    void printProgressChanged(const float &newProgress);
+    void printProgressChanged(const float newProgress);
 
     /**
      * @brief New message was received from the printer
diff --git a/src/core/atcore.cpp b/src/core/atcore.cpp
--- a/src/core/atcore.cpp
+++ b/src/core/atcore.cpp
@@ -584,6 +584,9 @@
 
 void AtCore::setExtruderTemp(uint temp, uint extruder, bool andWait)
 {
+    temp = std::min<uint>(temp, 10000);
+    extruder = std::min<uint>(extruder, 10000);
+
     if (andWait) {
         pushCommand(GCode::toCommand(GCode::M109, QString::number(temp), QString::number(extruder)));
     } else {
@@ -593,6 +596,8 @@
 
 void AtCore::setBedTemp(uint temp, bool andWait)
 {
+    temp = std::min<uint>(temp, 10000);
+
     if (andWait) {
         pushCommand(GCode::toCommand(GCode::M190, QString::number(temp)));
     } else {
@@ -602,16 +607,21 @@
 
 void AtCore::setFanSpeed(uint speed, uint fanNumber)
 {
+    speed = std::min<uint>(speed, 10000);
+    fanNumber = std::min<uint>(fanNumber, 10000);
+
     pushCommand(GCode::toCommand(GCode::M106, QString::number(fanNumber), QString::number(speed)));
 }
 
 void AtCore::setPrinterSpeed(uint speed)
 {
+    speed = std::min<uint>(speed, 10000);
     pushCommand(GCode::toCommand(GCode::M220, QString::number(speed)));
 }
 
 void AtCore::setFlowRate(uint speed)
 {
+    speed = std::min<uint>(speed, 10000);
     pushCommand(GCode::toCommand(GCode::M221, QString::number(speed)));
 }
 
diff --git a/src/core/printthread.h b/src/core/printthread.h
--- a/src/core/printthread.h
+++ b/src/core/printthread.h
@@ -59,7 +59,7 @@
     /**
      * @brief The print job's progress has changed
      */
-    void printProgressChanged(float);
+    void printProgressChanged(const float);
 
     /**
      * @brief the next command of the job
diff --git a/src/core/printthread.cpp b/src/core/printthread.cpp
--- a/src/core/printthread.cpp
+++ b/src/core/printthread.cpp
@@ -138,8 +138,8 @@
     d->cline = d->gcodestream->readLine();
     qCDebug(PRINT_THREAD) << "Nextline:" << d->cline;
     d->stillSize -= d->cline.size() + 1; //remove read chars
-    d->printProgress = float(d->totalSize - d->stillSize) * 100.0 / float(d->totalSize);
-    qCDebug(PRINT_THREAD) << "progress:" << QString::number(d->printProgress);
+    d->printProgress = float(d->totalSize - d->stillSize) * 100 / float(d->totalSize);
+    qCDebug(PRINT_THREAD) << "progress:" << QString::number(double(d->printProgress));
     emit printProgressChanged(d->printProgress);
 
     if (d->cline.startsWith(QStringLiteral(";-"))) {
@@ -208,17 +208,17 @@
     } else if (parser.isSet(QStringLiteral("extruder temperature"))) {
         QStringList args = parser.positionalArguments().at(0).split(QLatin1Char(','));
         bool wait = !QString::compare(args.at(2).simplified(), QStringLiteral("true"), Qt::CaseInsensitive);
-        d->core->setExtruderTemp(args.at(0).toInt(), args.at(1).toInt(), wait);
+        d->core->setExtruderTemp(args.at(0).toUInt(), args.at(1).toUInt(), wait);
     } else if (parser.isSet(QStringLiteral("bed temperature"))) {
         QStringList args = parser.positionalArguments().at(0).split(QLatin1Char(','));
         bool wait = !QString::compare(args.at(1).simplified(), QStringLiteral("true"), Qt::CaseInsensitive);
-        d->core->setBedTemp(args.at(0).toInt(), wait);
+        d->core->setBedTemp(args.at(0).toUInt(), wait);
     } else if (parser.isSet(QStringLiteral("print speed"))) {
-        d->core->setPrinterSpeed(parser.positionalArguments().at(0).toInt());
+        d->core->setPrinterSpeed(parser.positionalArguments().at(0).toUInt());
     } else if (parser.isSet(QStringLiteral("fan speed"))) {
-        d->core->setFanSpeed(parser.positionalArguments().at(0).toInt(), parser.positionalArguments().at(1).toInt());
+        d->core->setFanSpeed(parser.positionalArguments().at(0).toUInt(), parser.positionalArguments().at(1).toUInt());
     } else if (parser.isSet(QStringLiteral("flow rate"))) {
-        d->core->setFlowRate(parser.positionalArguments().at(0).toInt());
+        d->core->setFlowRate(parser.positionalArguments().at(0).toUInt());
     } else if (parser.isSet(QStringLiteral("message"))) {
         d->core->showMessage(parser.positionalArguments().at(0));
     } else if (parser.isSet(QStringLiteral("command"))) {
diff --git a/src/widgets/printwidget.cpp b/src/widgets/printwidget.cpp
--- a/src/widgets/printwidget.cpp
+++ b/src/widgets/printwidget.cpp
@@ -121,6 +121,7 @@
 
 void PrintWidget::updateFanCount(const int count)
 {
+    comboFanSelect->clear();
     for (int i = 0; i < count; i++) {
         comboFanSelect->insertItem(i, tr("Fan %1 speed").arg(i));
     }
diff --git a/src/widgets/temperaturewidget.cpp b/src/widgets/temperaturewidget.cpp
--- a/src/widgets/temperaturewidget.cpp
+++ b/src/widgets/temperaturewidget.cpp
@@ -66,6 +66,7 @@
 
 void TemperatureWidget::updateExtruderCount(const int count)
 {
+    comboExtruderSelect->clear();
     for (int i = 0; i < count; i++) {
         comboExtruderSelect->insertItem(i, tr("Extruder %1").arg(i));
     }
diff --git a/unittests/atcoretests.cpp b/unittests/atcoretests.cpp
--- a/unittests/atcoretests.cpp
+++ b/unittests/atcoretests.cpp
@@ -144,7 +144,7 @@
 
 void AtCoreTests::testSerialTimerIntervalChanged()
 {
-    QSignalSpy sSpy(core, SIGNAL(serialTimerIntervalChanged(quint16)));
+    QSignalSpy sSpy(core, SIGNAL(serialTimerIntervalChanged(int)));
     QVERIFY(sSpy.isValid());
     core->setSerialTimerInterval(1000);
     core->setSerialTimerInterval(1000);