diff --git a/src/app/qgsjoindialog.cpp b/src/app/qgsjoindialog.cpp
index 94473d621f79..3293c2daaa1e 100644
--- a/src/app/qgsjoindialog.cpp
+++ b/src/app/qgsjoindialog.cpp
@@ -47,7 +47,7 @@ QgsJoinDialog::QgsJoinDialog( QgsVectorLayer* layer, QList<QgsMapLayer*> already
   mCacheInMemoryCheckBox->setChecked( true );
 
   QgsMapLayer *joinLayer = mJoinLayerComboBox->currentLayer();
-  if ( joinLayer->isValid() )
+  if ( joinLayer && joinLayer->isValid() )
   {
     mJoinFieldComboBox->setLayer( joinLayer );
     joinedLayerChanged( joinLayer );