diff --git a/src/context/applets/analyzer/plugin/AnalyzerBase.cpp b/src/context/applets/analyzer/plugin/AnalyzerBase.cpp
--- a/src/context/applets/analyzer/plugin/AnalyzerBase.cpp
+++ b/src/context/applets/analyzer/plugin/AnalyzerBase.cpp
@@ -68,8 +68,12 @@
 {
     DEBUG_BLOCK
 
-    m_worker->deleteLater();
-    m_worker = Q_NULLPTR;
+    if( m_worker )
+    {
+        m_worker->deleteLater();
+        m_worker = nullptr;
+    }
+
     m_workerThread.quit();
     m_workerThread.wait();
 }
diff --git a/src/context/applets/analyzer/plugin/BlockAnalyzer.cpp b/src/context/applets/analyzer/plugin/BlockAnalyzer.cpp
--- a/src/context/applets/analyzer/plugin/BlockAnalyzer.cpp
+++ b/src/context/applets/analyzer/plugin/BlockAnalyzer.cpp
@@ -20,8 +20,8 @@
 #include "AnalyzerWorker.h"
 #include "BlockRenderer.h"
 #include "BlockWorker.h"
-
 #include "PaletteHandler.h"
+#include "core/support/Debug.h"
 
 #include <cmath>
 
diff --git a/src/context/applets/analyzer/plugin/BlockRenderer.h b/src/context/applets/analyzer/plugin/BlockRenderer.h
--- a/src/context/applets/analyzer/plugin/BlockRenderer.h
+++ b/src/context/applets/analyzer/plugin/BlockRenderer.h
@@ -26,21 +26,20 @@
 
 #include "BlockAnalyzer.h"
 #include "BlockWorker.h"
-#include "core/support/Debug.h"
 
 #include <QOpenGLFramebufferObject>
 #include <QOpenGLPaintDevice>
 #include <QPainter>
+#include <QPointer>
 #include <QQuickFramebufferObject>
-#include <QSGTexture>
-#include <QSharedPointer>
+
 
 class BlockRenderer : public QQuickFramebufferObject::Renderer
 {
 public:
     static const int BLOCK_HEIGHT = BlockAnalyzer::BLOCK_HEIGHT;
 
-    BlockRenderer() {}
+    BlockRenderer() : m_worker( nullptr ) {}
 
 protected:
     QOpenGLFramebufferObject* createFramebufferObject(const QSize &size) override
@@ -52,29 +51,38 @@
 
     void render() override
     {
+        // Synchronize worker data
+        if (!m_worker)
+            return;
+
+        m_worker->m_mutex.lock();
+        const QVector<double> store = m_worker->m_store;
+        const QVector<QList<BlockWorker::Fadebar> > fadebars = m_worker->m_fadebars;
+        m_worker->m_mutex.unlock();
+
         QOpenGLPaintDevice d;
         d.setSize(framebufferObject()->size());
         QPainter p(&d);
 
         // Draw the background
         p.drawPixmap(QRect(QPoint(0, 0), framebufferObject()->size()), m_backgroundPixmap);
 
-        for( uint x = 0; x < (uint)m_store.size(); ++x )
+        for(uint x = 0; x < (uint)store.size(); ++x)
         {
             // Draw fade bars
-            for( const auto &fadebar : m_fadebars.at(x) )
+            for(const auto &fadebar : qAsConst(fadebars.at(x)))
             {
-                if( fadebar.intensity > 0 )
+                if(fadebar.intensity > 0)
                 {
                     const uint offset = fadebar.intensity;
                     const int fadeHeight = fadebar.y * (BLOCK_HEIGHT + 1);
-                    if( fadeHeight > 0 )
-                        p.drawPixmap(x * ( m_columnWidth + 1 ), 0, m_fadeBarsPixmaps.value(offset), 0, 0, m_columnWidth, fadeHeight);
+                    if(fadeHeight > 0)
+                        p.drawPixmap(x * (m_columnWidth + 1), 0, m_fadeBarsPixmaps.value(offset), 0, 0, m_columnWidth, fadeHeight);
                 }
             }
 
             // Draw bars
-            const int height = m_store.at(x) * (BLOCK_HEIGHT + 1);
+            const int height = store.at(x) * (BLOCK_HEIGHT + 1);
             if (height > 0)
                 p.drawPixmap(x * (m_columnWidth + 1), 0, m_barPixmap, 0, 0, m_columnWidth, height);
 
@@ -92,14 +100,8 @@
         m_rows = analyzer->m_rows;
         m_columnWidth = analyzer->m_columnWidth;
 
-        auto worker = qobject_cast<const BlockWorker*>(analyzer->worker());
-        if (worker)
-        {
-            worker->m_mutex.lock();
-            m_store = worker->m_store;
-            m_fadebars = worker->m_fadebars;
-            worker->m_mutex.unlock();
-        }
+        if (!m_worker)
+            m_worker = qobject_cast<const BlockWorker*>(analyzer->worker());
 
         if (analyzer->m_pixmapsChanged)
         {
@@ -113,8 +115,8 @@
     }
 
 private:
-    QVector<double> m_store;
-    QVector<QList<BlockWorker::Fadebar> > m_fadebars;
+    QPointer<const BlockWorker> m_worker;
+
     int m_rows;
     int m_columnWidth;
 
diff --git a/src/context/applets/analyzer/plugin/BlockWorker.cpp b/src/context/applets/analyzer/plugin/BlockWorker.cpp
--- a/src/context/applets/analyzer/plugin/BlockWorker.cpp
+++ b/src/context/applets/analyzer/plugin/BlockWorker.cpp
@@ -61,7 +61,7 @@
     m_mutex.unlock();
 }
 
-void BlockWorker::setColumns(int columns)
+void BlockWorker::setColumns( int columns )
 {
     if( m_columns == columns )
         return;
@@ -85,8 +85,8 @@
     const qreal step = m_step * timeElapsed / 1000.0;
     const qreal fadeStep = (qreal)timeElapsed / 20.0;
 
-    // block m_store and m_fadebars
-    QMutexLocker locker(&m_mutex);
+    // lock m_store and m_fadebars
+    QMutexLocker locker( &m_mutex );
 
     m_store.resize( scopeSize );
     m_fadebars.resize( scopeSize );
@@ -102,7 +102,7 @@
         auto &store = m_store[x];
 
         // remove obscured fadebars
-        while( !fadebars.isEmpty() && fadebars.last().y >= y )
+        while( !fadebars.isEmpty() && fadebars.last().y <= y )
             fadebars.removeLast();
 
         // remove completely faded fadebars