diff --git a/src/comm/MAVLinkSimulationWaypointPlanner.cc b/src/comm/MAVLinkSimulationWaypointPlanner.cc
index 9ef3e8b437a04d3787b3221f451f6ab625f83edd..b35d7a3dc3d1a1cda45e1839e2a0e1c9dfef4ee5 100644
--- a/src/comm/MAVLinkSimulationWaypointPlanner.cc
+++ b/src/comm/MAVLinkSimulationWaypointPlanner.cc
@@ -35,6 +35,10 @@ This file is part of the PIXHAWK project
 #include "MAVLinkSimulationWaypointPlanner.h"
 #include "QGC.h"
 
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
 class PxMatrix3x3;
 
 
diff --git a/src/comm/SerialLink.cc b/src/comm/SerialLink.cc
index d6bc78ccfd40e48ca6ccdbf21672ce92c3b99ed8..7b97c51a52dc736ef16f24b8680345bd39ae35ca 100644
--- a/src/comm/SerialLink.cc
+++ b/src/comm/SerialLink.cc
@@ -297,6 +297,7 @@ bool SerialLink::connect()
             this->start(LowPriority);
         }
     }
+	return true;
 }
 
 /**
diff --git a/src/uas/SlugsMAV.h b/src/uas/SlugsMAV.h
index 50396a4175d4f235ad357e826d2bde09922c4036..7eca5054f2250bb0f707fda6c1ea7553673dde9c 100644
--- a/src/uas/SlugsMAV.h
+++ b/src/uas/SlugsMAV.h
@@ -36,7 +36,9 @@ class SlugsMAV : public UAS
 public:
     SlugsMAV(MAVLinkProtocol* mavlink, int id = 0);
 
+#ifdef MAVLINK_ENABLED_SLUGS
     mavlink_pwm_commands_t* getPwmCommands();
+#endif
 
 public slots:
     /** @brief Receive a MAVLink message from this MAV */
diff --git a/src/ui/SlugsHilSim.cc b/src/ui/SlugsHilSim.cc
index bec83ea050975990412794f767a6606fec761a9f..58849e56321fb3816d4a3143ed222d87b00b1413 100644
--- a/src/ui/SlugsHilSim.cc
+++ b/src/ui/SlugsHilSim.cc
@@ -51,12 +51,14 @@ SlugsHilSim::SlugsHilSim(QWidget *parent) :
 
     linksAvailable.clear();
 
+	#ifdef MAVLINK_ENABLED_SLUGS
     memset(&tmpAirData, 0, sizeof(mavlink_air_data_t));
     memset(&tmpAttitudeData, 0, sizeof(mavlink_attitude_t));
     memset(&tmpGpsData, 0, sizeof(mavlink_gps_raw_t));
     memset(&tmpGpsTime, 0, sizeof(mavlink_gps_date_time_t));
     memset(&tmpLocalPositionData, 0, sizeof(mavlink_sensor_bias_t));
     memset(&tmpRawImuData, 0, sizeof(mavlink_raw_imu_t));
+	#endif
 
     foreach (LinkInterface* link, LinkManager::instance()->getLinks())
     {
@@ -263,6 +265,7 @@ void SlugsHilSim::linkSelected(int cbIndex){
 
 void SlugsHilSim::sendMessageToSlugs()
 {
+	#ifdef MAVLINK_ENABLED_SLUGS
     mavlink_message_t msg;
 
     mavlink_msg_local_position_encode(MG::SYSTEM::ID,
@@ -306,11 +309,13 @@ void SlugsHilSim::sendMessageToSlugs()
                                     &tmpGpsTime);
     activeUas->sendMessage(hilLink, msg);
     memset(&msg, 0, sizeof(mavlink_message_t));
+#endif
 }
 
 
 void SlugsHilSim::commandDatagramToSimulink()
 {
+	#ifdef MAVLINK_ENABLED_SLUGS
     //mavlink_pwm_commands_t* pwdC = (static_cast<SlugsMAV*>(activeUas))->getPwmCommands();
 
     mavlink_pwm_commands_t* pwdC;
@@ -335,6 +340,7 @@ void SlugsHilSim::commandDatagramToSimulink()
     setUInt16ToDatagram(data, &i, 11);//value default
 
     txSocket->writeDatagram(data, QHostAddress::Broadcast, ui->ed_txPort->text().toInt());
+#endif
 }
 
 void SlugsHilSim::setUInt16ToDatagram(QByteArray& datagram, unsigned char* pos, uint16_t value)
diff --git a/src/ui/SlugsHilSim.h b/src/ui/SlugsHilSim.h
index 16f42f223b953844d7210f2bec840fc84d2134e7..b89ee1a68d1568a706af7a632a2d01eacdab4dab 100644
--- a/src/ui/SlugsHilSim.h
+++ b/src/ui/SlugsHilSim.h
@@ -69,9 +69,13 @@ protected:
     mavlink_local_position_t tmpLocalPositionData;
     mavlink_attitude_t tmpAttitudeData;
     mavlink_raw_imu_t tmpRawImuData;
+#ifdef MAVLINK_ENABLED_SLUGS
     mavlink_air_data_t tmpAirData;
+#endif
     mavlink_gps_raw_t tmpGpsData;
+	#ifdef MAVLINK_ENABLED_SLUGS
     mavlink_gps_date_time_t tmpGpsTime;
+#endif
 
 public slots:
 
@@ -150,4 +154,4 @@ private:
 
 };
 
-#endif // SLUGSHILSIM_H
+#endif // SLUGSHILSIM_H
\ No newline at end of file