diff --git a/.travis.yml b/.travis.yml
index b3b21d3479e2d95d6f21fb1c754952902bda2b0e..9b6acfa582c9fd71b83920cb2c9586ebba09c094 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -50,7 +50,7 @@ install:
     fi
 
 
-before_script: qmake -r qgroundcontrol.pro CONFIG+=${CONFIG} -spec ${SPEC}
+before_script: qmake -r qgroundcontrol.pro CONFIG+=${CONFIG} CONFIG+=WarningsAsErrorsOn -spec ${SPEC}
 script:
   - echo 'Building QGroundControl' && echo -en 'travis_fold:start:script.1\\r'
   - make -j4
diff --git a/src/AutoPilotPlugins/PX4/RadioComponentController.cc b/src/AutoPilotPlugins/PX4/RadioComponentController.cc
index f18f2055a4148a1fa88ffa9a8e1ce986f1f57437..e251c253264e30b9469df8e61ec5d7949c12cb60 100644
--- a/src/AutoPilotPlugins/PX4/RadioComponentController.cc
+++ b/src/AutoPilotPlugins/PX4/RadioComponentController.cc
@@ -624,7 +624,7 @@ void RadioComponentController::_inputFlapsDetect(enum rcCalFunctions function, i
 void RadioComponentController::_resetInternalCalibrationValues(void)
 {
     // Set all raw channels to not reversed and center point values
-    for (size_t i=0; i<_chanMax; i++) {
+    for (int i=0; i<_chanMax; i++) {
         struct ChannelInfo* info = &_rgChannelInfo[i];
         info->function = rcCalFunctionMax;
         info->reversed = false;
@@ -673,7 +673,7 @@ void RadioComponentController::_setInternalCalibrationValuesFromParameters(void)
 {
     // Initialize all function mappings to not set
     
-    for (size_t i=0; i<_chanMax; i++) {
+    for (int i=0; i<_chanMax; i++) {
         struct ChannelInfo* info = &_rgChannelInfo[i];
         info->function = rcCalFunctionMax;
     }
@@ -865,7 +865,7 @@ void RadioComponentController::_stopCalibration(void)
 void RadioComponentController::_rcCalSaveCurrentValues(void)
 {
 	qCDebug(RadioComponentControllerLog) << "_rcCalSaveCurrentValues";
-    for (unsigned i = 0; i < _chanMax; i++) {
+    for (int i = 0; i < _chanMax; i++) {
         _rcValueSave[i] = _rcRawValue[i];
     }
 }
diff --git a/src/VehicleSetup/FirmwareUpgradeController.cc b/src/VehicleSetup/FirmwareUpgradeController.cc
index 66992cdc37e580b1b48ee53988e480a6f4592c62..852c997633f0145689c15589c53ec323e8a27833 100644
--- a/src/VehicleSetup/FirmwareUpgradeController.cc
+++ b/src/VehicleSetup/FirmwareUpgradeController.cc
@@ -206,7 +206,7 @@ void FirmwareUpgradeController::_getFirmwareFile(FirmwareType_t firmwareType)
     // Select the firmware set based on board type
     
     const DownloadLocationByFirmwareType_t* prgFirmware;
-    size_t crgFirmware;
+    size_t crgFirmware = 0;
     
     switch (_bootloaderBoardID) {
         case Bootloader::boardIDPX4FMUV1:
diff --git a/src/VehicleSetup/JoystickConfigController.cc b/src/VehicleSetup/JoystickConfigController.cc
index 66942d2ed54b372656aee69f1f06374e9975bada..41dc552dd2db403cba8636176647cdb963dbe610 100644
--- a/src/VehicleSetup/JoystickConfigController.cc
+++ b/src/VehicleSetup/JoystickConfigController.cc
@@ -411,7 +411,7 @@ void JoystickConfigController::_inputCenterWait(Joystick::AxisFunction_t functio
 void JoystickConfigController::_resetInternalCalibrationValues(void)
 {
     // Set all raw axiss to not reversed and center point values
-    for (size_t i=0; i<_axisMax; i++) {
+    for (int i=0; i<_axisMax; i++) {
         struct AxisInfo* info = &_rgAxisInfo[i];
         info->function = Joystick::maxFunction;
         info->reversed = false;
@@ -435,7 +435,7 @@ void JoystickConfigController::_setInternalCalibrationValuesFromSettings(void)
     
     // Initialize all function mappings to not set
     
-    for (size_t i=0; i<_axisMax; i++) {
+    for (int i=0; i<_axisMax; i++) {
         struct AxisInfo* info = &_rgAxisInfo[i];
         info->function = Joystick::maxFunction;
     }
@@ -580,7 +580,7 @@ void JoystickConfigController::_stopCalibration(void)
 void JoystickConfigController::_calSaveCurrentValues(void)
 {
 	qCDebug(JoystickConfigControllerLog) << "_calSaveCurrentValues";
-    for (unsigned i = 0; i < _axisMax; i++) {
+    for (int i = 0; i < _axisMax; i++) {
         _axisValueSave[i] = _axisRawValue[i];
     }
 }