diff --git a/QGCExternalLibs.pri b/QGCExternalLibs.pri
index cfc3685e1b36dd003c97ae154a756b2d7e0d37d8..b5fb920c6c434acac1b54502e7aa54e2a894d381 100644
--- a/QGCExternalLibs.pri
+++ b/QGCExternalLibs.pri
@@ -532,24 +532,27 @@ MacBuild {
 #
 contains (DEFINES, DISABLE_SPEECH) {
 	message("Skipping support for speech output (manual override)")
+	DEFINES -= DISABLE_SPEECH
 } else:LinuxBuild {
 	exists(/usr/include/flite) | exists(/usr/local/include/flite) {
 		message("Including support for speech output")
+		DEFINES += QGC_SPEECH_ENABLED
 		LIBS += \
 		-lflite_cmu_us_kal \
 		-lflite_usenglish \
 		-lflite_cmulex \
 		-lflite
 	} else {
-		DEFINES += DISABLE_SPEECH
 		warning("Skipping support for speech output (missing libraries, see README)")
 	}
 }
 # Mac support is built into OS 10.6+.
 else:MacBuild {
 	message("Including support for speech output")
+	DEFINES += QGC_SPEECH_ENABLED
 }
 # Windows supports speech through native API.
 else:WindowsBuild {
 	message("Including support for speech output")
+	DEFINES += QGC_SPEECH_ENABLED
 }
diff --git a/src/GAudioOutput.cc b/src/GAudioOutput.cc
index 3dfa5314218cdb3f41689b167294ab11ae39913d..fd360796301b83d80ee7ead2d8c0571fb952d470 100644
--- a/src/GAudioOutput.cc
+++ b/src/GAudioOutput.cc
@@ -37,12 +37,12 @@ This file is part of the QGROUNDCONTROL project
 
 #include <QDebug>
 
-#if defined Q_OS_MAC && !defined DISABLE_SPEECH
+#if defined Q_OS_MAC && defined QGC_SPEECH_ENABLED
 #include <ApplicationServices/ApplicationServices.h>
 #endif
 
 // Speech synthesis is only supported with MSVC compiler
-#if defined _MSC_VER && !defined DISABLE_SPEECH
+#if defined _MSC_VER && defined QGC_SPEECH_ENABLED
 // Documentation: http://msdn.microsoft.com/en-us/library/ee125082%28v=VS.85%29.aspx
 #include <sapi.h>
 
@@ -50,14 +50,14 @@ This file is part of the QGROUNDCONTROL project
 //using System.Speech.Synthesis;
 #endif
 
-#if defined Q_OS_LINUX && !defined DISABLE_SPEECH
+#if defined Q_OS_LINUX && defined QGC_SPEECH_ENABLED
 extern "C" {
 #include <flite/flite.h>
     cst_voice *register_cmu_us_kal(const char *voxdir);
 };
 #endif
 
-#if defined _MSC_VER && !defined DISABLE_SPEECH
+#if defined _MSC_VER && defined QGC_SPEECH_ENABLED
 ISpVoice *GAudioOutput::pVoice = NULL;
 #endif
 
@@ -96,11 +96,11 @@ GAudioOutput::GAudioOutput(QObject *parent) : QObject(parent),
     muted = settings.value(QGC_GAUDIOOUTPUT_KEY + "muted", muted).toBool();
 
 
-#if defined Q_OS_LINUX && !defined DISABLE_SPEECH
+#if defined Q_OS_LINUX && defined QGC_SPEECH_ENABLED
     flite_init();
 #endif
 
-#if defined _MSC_VER && !defined DISABLE_SPEECH
+#if defined _MSC_VER && defined QGC_SPEECH_ENABLED
     pVoice = NULL;
 
     if (FAILED(::CoInitialize(NULL)))
@@ -145,7 +145,7 @@ GAudioOutput::GAudioOutput(QObject *parent) : QObject(parent),
 
 GAudioOutput::~GAudioOutput()
 {
-#if defined _MSC_VER && !defined DISABLE_SPEECH
+#if defined _MSC_VER && defined QGC_SPEECH_ENABLED
     pVoice->Release();
     pVoice = NULL;
     ::CoUninitialize();
@@ -182,7 +182,7 @@ bool GAudioOutput::say(QString text, int severity)
         {
 
             // Speech synthesis is only supported with MSVC compiler
-#if defined _MSC_VER && !defined DISABLE_SPEECH
+#if defined _MSC_VER && defined QGC_SPEECH_ENABLED
             /*SpeechSynthesizer synth = new SpeechSynthesizer();
             synth.SelectVoice("Microsoft Anna");
             synth.SpeakText(text.toStdString().c_str());
@@ -205,7 +205,7 @@ bool GAudioOutput::say(QString text, int severity)
             }*/
 #endif
 
-#if defined Q_OS_LINUX && !defined DISABLE_SPEECH
+#if defined Q_OS_LINUX && defined QGC_SPEECH_ENABLED
             QTemporaryFile file;
             file.setFileTemplate("XXXXXX.wav");
 
@@ -222,7 +222,7 @@ bool GAudioOutput::say(QString text, int severity)
 
 #endif
 
-#if defined Q_OS_MAC && !defined DISABLE_SPEECH
+#if defined Q_OS_MAC && defined QGC_SPEECH_ENABLED
             // Slashes necessary to have the right start to the sentence
             // copying data prevents SpeakString from reading additional chars
             text = "\\" + text;
@@ -339,14 +339,14 @@ void GAudioOutput::beep()
 
 void GAudioOutput::selectFemaleVoice()
 {
-#if defined Q_OS_LINUX && !defined DISABLE_SPEECH
+#if defined Q_OS_LINUX && defined QGC_SPEECH_ENABLED
     //this->voice = register_cmu_us_slt(NULL);
 #endif
 }
 
 void GAudioOutput::selectMaleVoice()
 {
-#if defined Q_OS_LINUX && !defined DISABLE_SPEECH
+#if defined Q_OS_LINUX && defined QGC_SPEECH_ENABLED
     //this->voice = register_cmu_us_rms(NULL);
 #endif
 }
@@ -354,7 +354,7 @@ void GAudioOutput::selectMaleVoice()
 /*
 void GAudioOutput::selectNeutralVoice()
 {
-#if defined Q_OS_LINUX && !defined DISABLE_SPEECH
+#if defined Q_OS_LINUX && defined QGC_SPEECH_ENABLED
     this->voice = register_cmu_us_awb(NULL);
 #endif
 }*/
diff --git a/src/GAudioOutput.h b/src/GAudioOutput.h
index 020ccea7c000b7433ad2dd78f6179162177a9fcb..456ba9765441f9a95aad76d679a349eac843f0cf 100644
--- a/src/GAudioOutput.h
+++ b/src/GAudioOutput.h
@@ -40,7 +40,7 @@ This file is part of the PIXHAWK project
 #include <AudioOutput>
 #endif
 #ifdef Q_OS_LINUX
-#if !defined DISABLE_SPEECH
+#if defined QGC_SPEECH_ENABLED
 //#include <flite/flite.h>
 #endif
 #include <phonon/MediaObject>
@@ -52,13 +52,13 @@ This file is part of the PIXHAWK project
 #endif
 
 /* For Snow leopard and later
-#if defined Q_OS_MAC & !defined DISABLE_SPEECH
+#if defined Q_OS_MAC & defined QGC_SPEECH_ENABLED
 #include <NSSpeechSynthesizer.h>
 #endif
    */
 
 
-#if defined _MSC_VER && !defined DISABLE_SPEECH
+#if defined _MSC_VER && defined QGC_SPEECH_ENABLED
 // Documentation: http://msdn.microsoft.com/en-us/library/ee125082%28v=VS.85%29.aspx
 #include <sapi.h>
 #endif
@@ -111,13 +111,13 @@ signals:
     void mutedChanged(bool);
 
 protected:
-#if defined Q_OS_MAC && !defined DISABLE_SPEECH
+#if defined Q_OS_MAC && defined QGC_SPEECH_ENABLED
     //NSSpeechSynthesizer
 #endif
-#if defined Q_OS_LINUX && !defined DISABLE_SPEECH
+#if defined Q_OS_LINUX && defined QGC_SPEECH_ENABLED
     //cst_voice* voice; ///< The flite voice object
 #endif
-#if defined _MSC_VER && !defined DISABLE_SPEECH
+#if defined _MSC_VER && defined QGC_SPEECH_ENABLED
     static ISpVoice *pVoice;
 #endif
     int voiceIndex;   ///< The index of the flite voice to use (awb, slt, rms)