diff --git a/Code/Mantid/MantidPlot/src/ApplicationWindow.cpp b/Code/Mantid/MantidPlot/src/ApplicationWindow.cpp
index df9466f3f6e4..2beb4f8c1fe1 100644
--- a/Code/Mantid/MantidPlot/src/ApplicationWindow.cpp
+++ b/Code/Mantid/MantidPlot/src/ApplicationWindow.cpp
@@ -7660,7 +7660,9 @@ void ApplicationWindow::exportPDF()
   if (!w)
     return;
 
-  if (w->isA("MultiLayer") && (dynamic_cast<MultiLayer*>(w))->isEmpty()){
+  auto ml = dynamic_cast<MultiLayer*>(w);
+
+  if (w->isA("MultiLayer") && ml && ml->isEmpty()) {
     QMessageBox::warning(this,tr("MantidPlot - Warning"),//Mantid
         tr("<h4>There are no plot layers available in this window.</h4>"));
     return;