diff --git a/src/GAudioOutput.cc b/src/GAudioOutput.cc
index 6d35f6215871ce4fed3a47faa7c7bdea303f36bd..e10d7fa4dd53e71aefc5a7cf4e13aa0341b22685 100644
--- a/src/GAudioOutput.cc
+++ b/src/GAudioOutput.cc
@@ -41,7 +41,8 @@ This file is part of the QGROUNDCONTROL project
 #endif
 
 // Speech synthesis is only supported with MSVC compiler
-#if _MSC_VER
+#if _MSC_VER2
+// Documentation: http://msdn.microsoft.com/en-us/library/ee125082%28v=VS.85%29.aspx
 #include <sapi.h>
 using System;
 using System.Speech.Synthesis;
@@ -111,7 +112,7 @@ bool GAudioOutput::say(QString text, int severity)
     {
 
         // Speech synthesis is only supported with MSVC compiler
-#ifdef _MSC_VER
+#ifdef _MSC_VER2
         SpeechSynthesizer synth = new SpeechSynthesizer();
         synth.SelectVoice("Microsoft Anna");
         synth.SpeakText(text.toStdString().c_str());
diff --git a/src/MG.h b/src/MG.h
index bde9c3d37f1867fbbb5452ae51b486d241962ecc..2e82de2c0c956e42274002b2ca98c08328fc0a0d 100644
--- a/src/MG.h
+++ b/src/MG.h
@@ -264,7 +264,7 @@ namespace MG
          * @param screenDiameter The screen diameter in mm, e.g. 13.3" = 338 mm.
          */
         static void setPixelSize(int horizontalResolution, int verticalResolution, double screenDiameter) {
-            pixelSize = screenDiameter / sqrt((horizontalResolution^(2)) + (verticalResolution^(2)));
+            pixelSize = screenDiameter / sqrt(static_cast<float>(horizontalResolution*horizontalResolution + verticalResolution*verticalResolution));
         }
 
     private:
diff --git a/src/comm/MAVLinkSimulationLink.cc b/src/comm/MAVLinkSimulationLink.cc
index d63474ad6e5d4df04e490b90ed05f37c64d1e509..56337c48a7f64a48a16750e311597d68ad23ea8f 100644
--- a/src/comm/MAVLinkSimulationLink.cc
+++ b/src/comm/MAVLinkSimulationLink.cc
@@ -380,9 +380,9 @@ void MAVLinkSimulationLink::mainloop()
 
 
         // Move X Position
-        x = x*0.93f + 0.07f*(x+sin(QGC::groundTimeUsecs()) * 0.08f);
-        y = y*0.93f + 0.07f*(y+sin(QGC::groundTimeUsecs()) * 0.5f);
-        z = z*0.93f + 0.07f*(z+sin(QGC::groundTimeUsecs()*100000) * 0.1f);
+        x = x*0.93f + 0.07f*(x+sin(static_cast<float>(QGC::groundTimeUsecs()) * 0.08f));
+        y = y*0.93f + 0.07f*(y+sin(static_cast<float>(QGC::groundTimeUsecs()) * 0.5f));
+        z = z*0.93f + 0.07f*(z+sin(static_cast<float>(QGC::groundTimeUsecs()*0.001f)) * 0.1f);
         x = 5247273.0f;
         y = 465955.0f;
 //        x = (x > 5.0f) ? 5.0f : x;
diff --git a/src/uas/UAS.cc b/src/uas/UAS.cc
index 3b4f136189ef183b5cbed875b720ab93af2a6831..b895e5ad9f88d3d87f304e8f708484e2464a274e 100644
--- a/src/uas/UAS.cc
+++ b/src/uas/UAS.cc
@@ -729,7 +729,7 @@ quint64 UAS::getUnixTime(quint64 time)
     // 60 seconds
     // 1000 milliseconds
     // 1000 microseconds
-    else if (time < 1261440000000000LLU)
+    else if (time < 1261440000000000)
     {
         if (onboardTimeOffset == 0)
         {
diff --git a/src/ui/HDDisplay.cc b/src/ui/HDDisplay.cc
index 5d9a449154c8af3e6406eae0773b0fc52373c629..1f8f11208dc81f470b2dd070a03e365e6f162be4 100644
--- a/src/ui/HDDisplay.cc
+++ b/src/ui/HDDisplay.cc
@@ -38,7 +38,9 @@ This file is part of the PIXHAWK project
 #include "HDDisplay.h"
 #include "ui_HDDisplay.h"
 #include "MG.h"
-
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
 #include <QDebug>
 
 HDDisplay::HDDisplay(QStringList* plotList, QWidget *parent) :
diff --git a/src/ui/HSIDisplay.cc b/src/ui/HSIDisplay.cc
index e7b0944dfd1277845699e7335a9c85490111b1b6..a9a993a02dc1a2a65fbc84cddf1f1594a97df0bb 100644
--- a/src/ui/HSIDisplay.cc
+++ b/src/ui/HSIDisplay.cc
@@ -478,7 +478,7 @@ void HSIDisplay::updateSpeed(UASInterface* uas, double vx, double vy, double vz,
     this->vx = vx;
     this->vy = vy;
     this->vz = vz;
-    this->speed = sqrt(pow(vx, 2.0f) + pow(vy, 2.0f) + pow(vz, 2.0f));
+    this->speed = sqrt(pow(vx, 2.0) + pow(vy, 2.0) + pow(vz, 2.0));
 }
 
 void HSIDisplay::setBodySetpointCoordinateXY(double x, double y)
diff --git a/src/ui/HUD.cc b/src/ui/HUD.cc
index 2267a3f5148fcf015c2f0f494208efa62277c6a7..872f2b9659566cffd36883cd97fe28a144768bda 100644
--- a/src/ui/HUD.cc
+++ b/src/ui/HUD.cc
@@ -31,6 +31,9 @@ This file is part of the QGROUNDCONTROL project
 
 #include <QDebug>
 #include <cmath>
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
 #include <limits>
 
 #include "UASManager.h"
diff --git a/src/ui/WaypointView.cc b/src/ui/WaypointView.cc
index 7e5244a8b2f08c016da2f74069b586aff24f58b1..6732b0b79e175b5dfd1c3cdbbd73587b8b66ca8c 100644
--- a/src/ui/WaypointView.cc
+++ b/src/ui/WaypointView.cc
@@ -35,6 +35,9 @@ This file is part of the PIXHAWK project
 #include <QDebug>
 
 #include <cmath>    //M_PI
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
 
 #include "WaypointView.h"
 #include "ui_WaypointView.h"