diff --git a/gui/audiooutput.cpp b/gui/audiooutput.cpp
index 334921ea..2ce3510c 100644
--- a/gui/audiooutput.cpp
+++ b/gui/audiooutput.cpp
@@ -181,7 +181,7 @@ int AudioOutput::portAudioCbPrivate(void *outputBuffer, unsigned long nBufferFra
     uint64_t bytesToRead = m_bytesPerFrame * nBufferFrames;
     uint32_t availableSamples = nBufferFrames;
 
-    bool muteRequest = m_muteFlag | m_stopFlag;        // false == do unmute, true == do mute
+    bool muteRequest = m_muteFlag || m_stopFlag;        // false == do unmute, true == do mute
 
     if (AudioOutputPlaybackState::Muted == m_playbackState)
     {   // muted
@@ -788,7 +788,7 @@ qint64 AudioIODevice::readData(char *data, qint64 len)
     m_inFifoPtr->mutex.unlock();
 
     //qDebug() << Q_FUNC_INFO << len << count << static_cast<int>(m_playbackState);
-    bool muteRequest = m_muteFlag |  m_stopFlag;
+    bool muteRequest = m_muteFlag ||  m_stopFlag;
 
     //uint64_t bytesToRead = len;
     uint64_t bytesToRead = qMin(uint64_t(len), AUDIOOUTPUT_FADE_TIME_MS * m_sampleRate_kHz * m_bytesPerFrame);
diff --git a/gui/inputdevicesrc.h b/gui/inputdevicesrc.h
index 2cd3c022..34177791 100644
--- a/gui/inputdevicesrc.h
+++ b/gui/inputdevicesrc.h
@@ -44,6 +44,8 @@ class InputDeviceSRC
 class InputDeviceSRCFilter
 {
 public:
+    virtual ~InputDeviceSRCFilter() {}   // virtual destructor to avoid undefined behavior
+
     // reset filter and signal level
     virtual void reset() = 0;
 
diff --git a/gui/radiocontrol.cpp b/gui/radiocontrol.cpp
index e22bd241..1a341b7c 100644
--- a/gui/radiocontrol.cpp
+++ b/gui/radiocontrol.cpp
@@ -805,7 +805,7 @@ void RadioControl::startUserApplication(DabUserApplicationType uaType, bool star
         }
 
         // TODO: not found - try ensemble
-#warning "Debug - remove or make implementation clean"
+        // #warning "Debug - remove or make implementation clean"
         for (auto & service : serviceList)
         {
             if (!service.SId.isProgServiceId())
diff --git a/gui/servicelistitem.cpp b/gui/servicelistitem.cpp
index 63aaa790..d3f0e4bd 100644
--- a/gui/servicelistitem.cpp
+++ b/gui/servicelistitem.cpp
@@ -109,7 +109,7 @@ const EnsembleListItem * ServiceListItem::getEnsemble(int num) const
 {
     if (num < 0)
     {   // best ensemble
-#warning "Best ensemble to be implemented"
+        // #warning "Best ensemble to be implemented"
         return m_ensembleList.at(m_currentEnsemble);
     }
     else
diff --git a/gui/spiapp.cpp b/gui/spiapp.cpp
index ea15575d..695b960e 100644
--- a/gui/spiapp.cpp
+++ b/gui/spiapp.cpp
@@ -614,4 +614,6 @@ const uint8_t *SPIApp::parseAttributes(const uint8_t *attrPtr, uint8_t tag, int
     default:
         break;
     }
+
+    return nullptr;
 }