diff --git a/plugins/channeltx/modwfm/wfmmodsource.cpp b/plugins/channeltx/modwfm/wfmmodsource.cpp
index 60f929b18..d073c3260 100644
--- a/plugins/channeltx/modwfm/wfmmodsource.cpp
+++ b/plugins/channeltx/modwfm/wfmmodsource.cpp
@@ -26,20 +26,23 @@ WFMModSource::WFMModSource() :
     m_channelFrequencyOffset(0),
     m_modPhasor(0.0f),
     m_audioSampleRate(48000),
-    m_audioFifo(4800),
+    m_audioFifo(12000),
     m_feedbackAudioSampleRate(48000),
     m_feedbackAudioFifo(48000),
 	m_levelCalcCount(0),
 	m_peakLevel(0.0f),
 	m_levelSum(0.0f),
-    m_ifstream(nullptr)
+    m_ifstream(nullptr),
+    m_mutex(QMutex::Recursive)
 {
     m_rfFilter = new fftfilt(-62500.0 / 384000.0, 62500.0 / 384000.0, m_rfFilterFFTLength);
     m_rfFilterBuffer = new Complex[m_rfFilterFFTLength];
     std::fill(m_rfFilterBuffer, m_rfFilterBuffer+m_rfFilterFFTLength, Complex{0,0});
     m_rfFilterBufferIndex = 0;
-	m_audioBuffer.resize(1<<14);
+	m_audioBuffer.resize(24000);
 	m_audioBufferFill = 0;
+	m_audioReadBuffer.resize(24000);
+	m_audioReadBufferFill = 0;
 	m_magsq = 0.0;
 	m_feedbackAudioBuffer.resize(1<<14);
 	m_feedbackAudioBufferFill = 0;
@@ -160,12 +163,20 @@ void WFMModSource::prefetch(unsigned int nbSamples)
 
 void WFMModSource::pullAudio(unsigned int nbSamplesAudio)
 {
+    QMutexLocker mlock(&m_mutex);
+
     if (nbSamplesAudio > m_audioBuffer.size()) {
         m_audioBuffer.resize(nbSamplesAudio);
     }
 
-    m_audioFifo.read(reinterpret_cast<quint8*>(&m_audioBuffer[0]), nbSamplesAudio);
+    std::copy(&m_audioReadBuffer[0], &m_audioReadBuffer[nbSamplesAudio], &m_audioBuffer[0]);
     m_audioBufferFill = 0;
+
+    if (m_audioReadBufferFill > nbSamplesAudio) // copy back remaining samples at the start of the read buffer
+    {
+        std::copy(&m_audioReadBuffer[nbSamplesAudio], &m_audioReadBuffer[m_audioReadBufferFill], &m_audioReadBuffer[0]);
+        m_audioReadBufferFill = m_audioReadBufferFill - nbSamplesAudio; // adjust current read buffer fill pointer
+    }
 }
 
 void WFMModSource::pullAF(Real& sample)
@@ -372,6 +383,15 @@ void WFMModSource::applySettings(const WFMModSettings& settings, bool force)
         m_cwToneNco.setFreq(settings.m_toneFrequency, m_audioSampleRate);
     }
 
+    if ((settings.m_modAFInput != m_settings.m_modAFInput) || force)
+    {
+        if (settings.m_modAFInput == WFMModSettings::WFMModInputAudio) {
+            connect(&m_audioFifo, SIGNAL(dataReady()), this, SLOT(handleAudio()));
+        } else {
+            disconnect(&m_audioFifo, SIGNAL(dataReady()), this, SLOT(handleAudio()));
+        }
+    }
+
     m_settings = settings;
 }
 
@@ -401,3 +421,16 @@ void WFMModSource::applyChannelSettings(int channelSampleRate, int channelFreque
     m_channelSampleRate = channelSampleRate;
     m_channelFrequencyOffset = channelFrequencyOffset;
 }
+
+void WFMModSource::handleAudio()
+{
+    QMutexLocker mlock(&m_mutex);
+    unsigned int nbRead;
+
+    while ((nbRead = m_audioFifo.read(reinterpret_cast<quint8*>(&m_audioReadBuffer[m_audioReadBufferFill]), 4096)) != 0)
+    {
+        if (m_audioReadBufferFill + nbRead + 4096 < m_audioReadBuffer.size()) {
+            m_audioReadBufferFill += nbRead;
+        }
+    }
+}
diff --git a/plugins/channeltx/modwfm/wfmmodsource.h b/plugins/channeltx/modwfm/wfmmodsource.h
index e263f74f7..3b393e623 100644
--- a/plugins/channeltx/modwfm/wfmmodsource.h
+++ b/plugins/channeltx/modwfm/wfmmodsource.h
@@ -18,6 +18,7 @@
 #ifndef INCLUDE_WFMMODSOURCE_H
 #define INCLUDE_WFMMODSOURCE_H
 
+#include <QObject>
 #include <QMutex>
 
 #include <iostream>
@@ -34,8 +35,9 @@
 
 #include "wfmmodsettings.h"
 
-class WFMModSource : public ChannelSampleSource
+class WFMModSource : public QObject, public ChannelSampleSource
 {
+    Q_OBJECT
 public:
     WFMModSource();
     virtual ~WFMModSource();
@@ -93,7 +95,9 @@ private:
 
     int m_audioSampleRate;
     AudioVector m_audioBuffer;
-    uint m_audioBufferFill;
+    unsigned int m_audioBufferFill;
+    AudioVector m_audioReadBuffer;
+    unsigned int m_audioReadBufferFill;
     AudioFifo m_audioFifo;
 
     int m_feedbackAudioSampleRate;
@@ -110,6 +114,8 @@ private:
     std::ifstream *m_ifstream;
     CWKeyer m_cwKeyer;
 
+    QMutex m_mutex;
+
     static const int m_levelNbSamples;
 
     void processOneSample(Complex& ci);
@@ -118,6 +124,9 @@ private:
     void pushFeedback(Complex sample);
     void calculateLevel(const Real& sample);
     void modulateAudio();
+
+private slots:
+    void handleAudio();
 };
 
 #endif // INCLUDE_WFMMODSOURCE_H