diff --git a/src/audio/audio.cpp b/src/audio/audio.cpp
index 44ac4ad2e..62dfdb203 100644
--- a/src/audio/audio.cpp
+++ b/src/audio/audio.cpp
@@ -48,6 +48,15 @@
  #include <AL/alc.h>
 #endif
 
+#ifndef ALC_ALL_DEVICES_SPECIFIER
+// compatibility with older versions of OpenAL
+#include <AL/alext.h>
+#endif
+
+#ifdef QTOX_FILTER_AUDIO
+#include "audiofilterer.h"
+#endif
+
 Audio* Audio::instance{nullptr};
 
 class AudioPrivate
@@ -77,7 +86,6 @@ public:
     ALCdevice*      alOutDev;
     ALCcontext*     alContext;
 
-    // predefined sources
     ALuint          alMainSource;
 
     qreal inputVolume;
@@ -792,7 +800,7 @@ bool Audio::tryCaptureSamples(int16_t* buf, int samples)
     if (!(d->alInDev && d->inputInitialized))
         return false;
 
-    ALint curSamples=0;
+    ALint curSamples = 0;
     alcGetIntegerv(d->alInDev, ALC_CAPTURE_SAMPLES, sizeof(curSamples), &curSamples);
     if (curSamples < samples)
         return false;
@@ -814,29 +822,19 @@ bool Audio::tryCaptureSamples(int16_t* buf, int samples)
     return true;
 }
 
-#ifdef QTOX_FILTER_AUDIO
-#include "audiofilterer.h"
-
-/* include for compatibility with older versions of OpenAL */
-#ifndef ALC_ALL_DEVICES_SPECIFIER
-#include <AL/alext.h>
-#endif
-
-void Audio::getEchoesToFilter(AudioFilterer* filterer, int framesize)
+#if defined(QTOX_FILTER_AUDIO) && defined(ALC_LOOPBACK_CAPTURE_SAMPLES)
+void Audio::getEchoesToFilter(AudioFilterer* filterer, int samples)
 {
-#ifdef ALC_LOOPBACK_CAPTURE_SAMPLES
+    QMutexLocker locker(&d->audioLock);
+
     ALint samples;
-    alcGetIntegerv(Audio::getInstance().alOutDev, ALC_LOOPBACK_CAPTURE_SAMPLES, sizeof(samples), &samples);
-    if (samples >= framesize)
+    alcGetIntegerv(&d->alOutDev, ALC_LOOPBACK_CAPTURE_SAMPLES, sizeof(samples), &samples);
+    if (samples >= samples)
     {
-        int16_t buf[framesize];
-        alcCaptureSamplesLoopback(Audio::getInstance().alOutDev, buf, framesize);
-        filterer->passAudioOutput(buf, framesize);
+        int16_t buf[samples];
+        alcCaptureSamplesLoopback(&d->alOutDev, buf, samples);
+        filterer->passAudioOutput(buf, samples);
         filterer->setEchoDelayMs(5); // This 5ms is configurable I believe
     }
-#else
-    Q_UNUSED(filterer);
-    Q_UNUSED(framesize);
-#endif
 }
 #endif
diff --git a/src/audio/audio.h b/src/audio/audio.h
index c981b9564..7aa397ed3 100644
--- a/src/audio/audio.h
+++ b/src/audio/audio.h
@@ -82,9 +82,8 @@ public:
     static void playGroupAudioQueued(void *, int group, int peer, const int16_t* data,
                                      unsigned samples, uint8_t channels, unsigned sample_rate, void*);
 
-#ifdef QTOX_FILTER_AUDIO
-    static void getEchoesToFilter(AudioFilterer* filter, int framesize);
-    // is a null op #ifndef ALC_LOOPBACK_CAPTURE_SAMPLES
+#if defined(QTOX_FILTER_AUDIO) && defined(ALC_LOOPBACK_CAPTURE_SAMPLES)
+    void getEchoesToFilter(AudioFilterer* filter, int samples);
 #endif
 
 public slots:
diff --git a/src/core/coreav.cpp b/src/core/coreav.cpp
index ffe45729a..6c3a15ef8 100644
--- a/src/core/coreav.cpp
+++ b/src/core/coreav.cpp
@@ -263,9 +263,11 @@ bool CoreAV::sendCallAudio(uint32_t callId)
                 call.filterer = new AudioFilterer();
                 call.filterer->startFilter(AUDIO_SAMPLE_RATE);
             }
-            // is a null op #ifndef ALC_LOOPBACK_CAPTURE_SAMPLES
-            Audio::getEchoesToFilter(call.filterer, AUDIO_FRAME_SAMPLE_COUNT * AUDIO_CHANNELS);
 
+#ifdef ALC_LOOPBACK_CAPTURE_SAMPLES
+            // compatibility with older versions of OpenAL
+            Audio::getInstance().getEchoesToFilter(call.filterer, AUDIO_FRAME_SAMPLE_COUNT * AUDIO_CHANNELS);
+#endif
             call.filterer->filterAudio(buf, AUDIO_FRAME_SAMPLE_COUNT * AUDIO_CHANNELS);
         }
         else if (call.filterer)
@@ -413,10 +415,10 @@ bool CoreAV::sendGroupCallAudio(int groupId)
                 call.filterer = new AudioFilterer();
                 call.filterer->startFilter(AUDIO_SAMPLE_RATE);
             }
-            // is a null op #ifndef ALC_LOOPBACK_CAPTURE_SAMPLES
-            Audio::getEchoesToFilter(call.filterer, AUDIO_FRAME_SAMPLE_COUNT);
 
-            call.filterer->filterAudio(buf, AUDIO_FRAME_SAMPLE_COUNT * AUDIO_CHANNELS);
+#ifdef ALC_LOOPBACK_CAPTURE_SAMPLES
+            Audio::getInstance().getEchoesToFilter(call.filterer, AUDIO_FRAME_SAMPLE_COUNT);
+#endif
         }
         else if (call.filterer)
         {