diff --git a/src/sdr/SDRPostThread.cpp b/src/sdr/SDRPostThread.cpp
index af5471d..afdc16f 100644
--- a/src/sdr/SDRPostThread.cpp
+++ b/src/sdr/SDRPostThread.cpp
@@ -16,12 +16,12 @@
 #define MAX_BLOCKING_DURATION_MICROS (1000 * 1000)
 
 SDRPostThread::SDRPostThread() : IOThread(), buffers("SDRPostThreadBuffers"), visualDataBuffers("SDRPostThreadVisualDataBuffers"), frequency(0) {
-    iqDataInQueue = NULL;
-    iqDataOutQueue = NULL;
-    iqVisualQueue = NULL;
+    iqDataInQueue = nullptr;
+    iqDataOutQueue = nullptr;
+    iqVisualQueue = nullptr;
 
     numChannels = 0;
-    channelizer = NULL;
+    channelizer = nullptr;
     
     sampleRate = 0;
     nRunDemods = 0;
@@ -92,7 +92,7 @@ void SDRPostThread::updateActiveDemodulators() {
             }
         } else if (!demod->isActive()) { // in range, activate if not activated
             demod->setActive(true);
-            if (wxGetApp().getDemodMgr().getLastActiveDemodulator() == NULL) {
+            if (wxGetApp().getDemodMgr().getLastActiveDemodulator() == nullptr) {
 
                 wxGetApp().getDemodMgr().setActiveDemodulator(demod);
             }
@@ -232,7 +232,7 @@ void SDRPostThread::runSingleCH(SDRThreadIQData *data_in) {
     
     size_t refCount = nRunDemods;
     bool doIQDataOut = (iqDataOutQueue != nullptr && !iqDataOutQueue->full());
-    bool doDemodVisOut = (nRunDemods && iqActiveDemodVisualQueue != NULL && !iqActiveDemodVisualQueue->full());
+    bool doDemodVisOut = (nRunDemods && iqActiveDemodVisualQueue != nullptr && !iqActiveDemodVisualQueue->full());
     bool doVisOut = (iqVisualQueue != nullptr && !iqVisualQueue->full());
     
     if (doIQDataOut) {
@@ -309,7 +309,7 @@ void SDRPostThread::runPFBCH(SDRThreadIQData *data_in) {
         
         bool doVis = false;
         
-        if (iqVisualQueue != NULL && !iqVisualQueue->full()) {
+        if (iqVisualQueue != nullptr && !iqVisualQueue->full()) {
             doVis = true;
         }
         
@@ -371,7 +371,7 @@ void SDRPostThread::runPFBCH(SDRThreadIQData *data_in) {
         
         // Run channels
         for (int i = 0; i < numChannels+1; i++) {
-            int doDemodVis = ((activeDemodChannel == i) && (iqActiveDemodVisualQueue != NULL) && !iqActiveDemodVisualQueue->full())?1:0;
+            int doDemodVis = ((activeDemodChannel == i) && (iqActiveDemodVisualQueue != nullptr) && !iqActiveDemodVisualQueue->full())?1:0;
             
             if (!doDemodVis && demodChannelActive[i] == 0) {
                 continue;
diff --git a/src/sdr/SoapySDRThread.cpp b/src/sdr/SoapySDRThread.cpp
index ece5e94..ecd1d54 100644
--- a/src/sdr/SoapySDRThread.cpp
+++ b/src/sdr/SoapySDRThread.cpp
@@ -13,10 +13,10 @@
 #define TARGET_DISPLAY_FPS 60
 
 SDRThread::SDRThread() : IOThread(), buffers("SDRThreadBuffers") {
-    device = NULL;
+    device = nullptr;
 
-    deviceConfig.store(NULL);
-    deviceInfo.store(NULL);
+    deviceConfig.store(nullptr);
+    deviceInfo.store(nullptr);
 
     sampleRate.store(DEFAULT_SAMPLE_RATE);
     frequency.store(0);
diff --git a/src/visual/TuningCanvas.cpp b/src/visual/TuningCanvas.cpp
index bbf601d..ba95132 100644
--- a/src/visual/TuningCanvas.cpp
+++ b/src/visual/TuningCanvas.cpp
@@ -331,7 +331,7 @@ void TuningCanvas::OnMouseMoved(wxMouseEvent& event) {
     if (hoverState == TUNING_HOVER_BW || hoverState == TUNING_HOVER_FREQ) {
          wxGetApp().getDemodMgr().setActiveDemodulator(wxGetApp().getDemodMgr().getLastActiveDemodulator());
      } else {
-         wxGetApp().getDemodMgr().setActiveDemodulator(NULL);
+         wxGetApp().getDemodMgr().setActiveDemodulator(nullptr);
      }
 }
 
@@ -401,7 +401,7 @@ void TuningCanvas::OnMouseLeftWindow(wxMouseEvent& event) {
     SetCursor(wxCURSOR_CROSS);
     hoverIndex = 0;
     hoverState = TUNING_HOVER_NONE;
-    wxGetApp().getDemodMgr().setActiveDemodulator(NULL);
+    wxGetApp().getDemodMgr().setActiveDemodulator(nullptr);
 
     if (currentPPM != lastPPM) {
         wxGetApp().saveConfig();
diff --git a/src/visual/WaterfallCanvas.cpp b/src/visual/WaterfallCanvas.cpp
index 9a36d2f..a951a1f 100644
--- a/src/visual/WaterfallCanvas.cpp
+++ b/src/visual/WaterfallCanvas.cpp
@@ -309,9 +309,9 @@ void WaterfallCanvas::OnPaint(wxPaintEvent& WXUNUSED(event)) {
             }
         } else {
             if (lastActiveDemodulator) {
-                glContext->DrawDemod(lastActiveDemodulator, ((isNew && activeDemodulator == NULL) || (activeDemodulator != NULL))?currentTheme->waterfallHighlight:currentTheme->waterfallDestroy, currentCenterFreq, currentBandwidth);
+                glContext->DrawDemod(lastActiveDemodulator, ((isNew && activeDemodulator == nullptr) || (activeDemodulator != nullptr))?currentTheme->waterfallHighlight:currentTheme->waterfallDestroy, currentCenterFreq, currentBandwidth);
             }
-            if (activeDemodulator == NULL) {
+            if (activeDemodulator == nullptr) {
                 glContext->DrawFreqSelector(mouseTracker.getMouseX(), ((isNew && lastActiveDemodulator) || (!lastActiveDemodulator) )?currentTheme->waterfallNew:currentTheme->waterfallHover, 0, currentCenterFreq, currentBandwidth);
             } else {
                 glContext->DrawDemod(activeDemodulator, currentTheme->waterfallHover, currentCenterFreq, currentBandwidth);
@@ -539,7 +539,7 @@ void WaterfallCanvas::updateHoverState() {
             }
         }
         
-        if (activeDemodulator == NULL) {
+        if (activeDemodulator == nullptr) {
             nextDragState = WF_DRAG_NONE;
             SetCursor(wxCURSOR_CROSS);
             return;
@@ -593,7 +593,7 @@ void WaterfallCanvas::OnMouseMoved(wxMouseEvent& event) {
     auto demod = wxGetApp().getDemodMgr().getActiveDemodulator();
 
     if (mouseTracker.mouseDown()) {
-        if (demod == NULL) {
+        if (demod == nullptr) {
             return;
         }
         if (dragState == WF_DRAG_BANDWIDTH_LEFT || dragState == WF_DRAG_BANDWIDTH_RIGHT) {
@@ -672,7 +672,7 @@ void WaterfallCanvas::OnMouseReleased(wxMouseEvent& event) {
     InteractiveCanvas::OnMouseReleased(event);
     wxGetApp().getDemodMgr().updateLastState();
 
-    bool isNew = shiftDown || (wxGetApp().getDemodMgr().getLastActiveDemodulator() == NULL)
+    bool isNew = shiftDown || (wxGetApp().getDemodMgr().getLastActiveDemodulator() == nullptr)
             || (wxGetApp().getDemodMgr().getLastActiveDemodulator() && !wxGetApp().getDemodMgr().getLastActiveDemodulator()->isActive());
 
     mouseTracker.setVertDragLock(false);
@@ -832,7 +832,7 @@ void WaterfallCanvas::OnMouseReleased(wxMouseEvent& event) {
             wxGetApp().notifyDemodulatorsChanged();
         }
 
-        if (demod == NULL) {
+        if (demod == nullptr) {
             dragState = WF_DRAG_NONE;
             return;
         }
@@ -852,7 +852,7 @@ void WaterfallCanvas::OnMouseReleased(wxMouseEvent& event) {
 void WaterfallCanvas::OnMouseLeftWindow(wxMouseEvent& event) {
     InteractiveCanvas::OnMouseLeftWindow(event);
     SetCursor(wxCURSOR_CROSS);
-    wxGetApp().getDemodMgr().setActiveDemodulator(NULL);
+    wxGetApp().getDemodMgr().setActiveDemodulator(nullptr);
     mouseZoom = 1.0;
 }