diff --git a/samplebuffer.cpp b/samplebuffer.cpp
index f550474..437eee7 100644
--- a/samplebuffer.cpp
+++ b/samplebuffer.cpp
@@ -29,6 +29,9 @@ template <typename Tin, typename Tout>
 std::unique_ptr<Tout[]> SampleBuffer<Tin, Tout>::getSamples(off_t start, off_t length)
 {
     auto samples = src->getSamples(start, length);
+    if (samples == nullptr)
+    	return nullptr;
+
     std::unique_ptr<Tout[]> dest(new Tout[length]);
     work(samples.get(), dest.get(), length);
     return dest;
diff --git a/traceplot.cpp b/traceplot.cpp
index 133c557..83b221c 100644
--- a/traceplot.cpp
+++ b/traceplot.cpp
@@ -32,6 +32,9 @@ void TracePlot::paintMid(QPainter &painter, QRect &rect, range_t<off_t> sampleRa
 	// Is it a 2-channel (complex) trace?
     if (auto src = dynamic_cast<SampleSource<std::complex<float>>*>(sampleSource.get())) {
         auto samples = src->getSamples(firstSample, length);
+        if (samples == nullptr)
+            return;
+
         painter.setPen(Qt::red);
         plotTrace(painter, rect, reinterpret_cast<float*>(samples.get()), length, 2);
         painter.setPen(Qt::blue);
@@ -40,6 +43,9 @@ void TracePlot::paintMid(QPainter &painter, QRect &rect, range_t<off_t> sampleRa
     // Otherwise is it single channel?
     } else if (auto src = dynamic_cast<SampleSource<float>*>(sampleSource.get())) {
         auto samples = src->getSamples(firstSample, length);
+        if (samples == nullptr)
+            return;
+
         painter.setPen(Qt::green);
         plotTrace(painter, rect, samples.get(), length, 1);
     } else {