diff --git a/toonz/sources/toonz/imageviewer.cpp b/toonz/sources/toonz/imageviewer.cpp
index 4abfd87..7d1aad0 100644
--- a/toonz/sources/toonz/imageviewer.cpp
+++ b/toonz/sources/toonz/imageviewer.cpp
@@ -730,6 +730,7 @@ void ImageViewer::updateCursor(const TPoint &curPos) {
 /*! If middle button is pressed pan the image. Update current mouse position.
 */
 void ImageViewer::mouseMoveEvent(QMouseEvent *event) {
+  if (!m_image) return;
   QPoint curQPos = event->pos() * getDevPixRatio();
 
   TPoint curPos = TPoint(curQPos.x(), curQPos.y());
@@ -947,6 +948,7 @@ int ImageViewer::getDragType(const TPoint &pos, const TRect &loadbox) {
 
 //-------------------------------------------------------------------------------
 void ImageViewer::mouseDoubleClickEvent(QMouseEvent *event) {
+  if (!m_image) return;
   if (m_visualSettings.m_defineLoadbox && m_flipbook) {
     m_flipbook->setLoadbox(TRect());
     update();
@@ -957,6 +959,7 @@ void ImageViewer::mouseDoubleClickEvent(QMouseEvent *event) {
 //------------------------------------------------------------------------------
 
 void ImageViewer::mousePressEvent(QMouseEvent *event) {
+  if (!m_image) return;
   m_pos                   = event->pos() * getDevPixRatio();
   m_pressedMousePos       = TPoint(m_pos.x(), m_pos.y());
   m_mouseButton           = event->button();
@@ -1004,6 +1007,7 @@ void ImageViewer::mousePressEvent(QMouseEvent *event) {
 /*! Reset current mouse position and current mouse button event.
 */
 void ImageViewer::mouseReleaseEvent(QMouseEvent *event) {
+  if (!m_image) return;
   if (m_draggingZoomSelection && !m_visualSettings.m_defineLoadbox) {
     m_draggingZoomSelection = false;
 
@@ -1039,6 +1043,7 @@ void ImageViewer::mouseReleaseEvent(QMouseEvent *event) {
 /*! Apply zoom.
 */
 void ImageViewer::wheelEvent(QWheelEvent *event) {
+  if (!m_image) return;
   if (event->orientation() == Qt::Horizontal) return;
   int delta = event->delta() > 0 ? 120 : -120;
   QPoint center(event->pos().x() * getDevPixRatio() - width() / 2,