diff --git a/effects/backgroundcontrast/contrast.cpp b/effects/backgroundcontrast/contrast.cpp
index 059a5d85fb..882055b651 100644
--- a/effects/backgroundcontrast/contrast.cpp
+++ b/effects/backgroundcontrast/contrast.cpp
@@ -230,6 +230,8 @@ void ContrastEffect::uploadRegion(QVector2D *&map, const QRegion &region)
 void ContrastEffect::uploadGeometry(GLVertexBuffer *vbo, const QRegion &region)
 {
     const int vertexCount = region.rectCount() * 6;
+    if (!vertexCount)
+        return;
 
     QVector2D *map = (QVector2D *) vbo->map(vertexCount * sizeof(QVector2D));
     uploadRegion(map, region);
diff --git a/effects/blur/blur.cpp b/effects/blur/blur.cpp
index e238bd2ed8..fe0d467b12 100644
--- a/effects/blur/blur.cpp
+++ b/effects/blur/blur.cpp
@@ -236,6 +236,8 @@ void BlurEffect::uploadRegion(QVector2D *&map, const QRegion &region)
 void BlurEffect::uploadGeometry(GLVertexBuffer *vbo, const QRegion &horizontal, const QRegion &vertical)
 {
     const int vertexCount = (horizontal.rectCount() + vertical.rectCount()) * 6;
+    if (!vertexCount)
+        return;
 
     QVector2D *map = (QVector2D *) vbo->map(vertexCount * sizeof(QVector2D));
     uploadRegion(map, horizontal);
diff --git a/effects/presentwindows/presentwindows.cpp b/effects/presentwindows/presentwindows.cpp
index eacdf24383..be62b619f7 100755
--- a/effects/presentwindows/presentwindows.cpp
+++ b/effects/presentwindows/presentwindows.cpp
@@ -135,6 +135,7 @@ void PresentWindowsEffect::reconfigure(ReconfigureFlags)
     if (m_doNotCloseWindows) {
         delete m_closeView;
         m_closeView = nullptr;
+        m_closeWindow = nullptr;
     }
     m_ignoreMinimized = PresentWindowsConfig::ignoreMinimized();
     m_accuracy = PresentWindowsConfig::accuracy() * 20;