diff --git a/toonz/sources/toonz/filmstrip.cpp b/toonz/sources/toonz/filmstrip.cpp
index 34ccd67..8fad7c6 100644
--- a/toonz/sources/toonz/filmstrip.cpp
+++ b/toonz/sources/toonz/filmstrip.cpp
@@ -486,11 +486,7 @@ void FilmstripFrames::hideEvent(QHideEvent *) {
   // active viewer change
   disconnect(app, SIGNAL(activeViewerChanged()), this, SLOT(getViewer()));
 
-  // if the level strip is floating during shutting down Tahoma2D
-  // it can cause a crash disconnecting from the viewer which was already
-  // destroyed.  Checking the fps is a janky way to ensure the viewer is 
-  // stil relevant.
-  if (m_viewer && m_viewer->getFPS() > -100) { 
+  if (m_viewer) {
     disconnect(m_viewer, SIGNAL(onZoomChanged()), this, SLOT(update()));
     disconnect(m_viewer, SIGNAL(refreshNavi()), this, SLOT(update()));
     m_viewer = nullptr;
@@ -505,6 +501,8 @@ void FilmstripFrames::getViewer() {
     if (m_viewer) {
       disconnect(m_viewer, SIGNAL(onZoomChanged()), this, SLOT(update()));
       disconnect(m_viewer, SIGNAL(refreshNavi()), this, SLOT(update()));
+      disconnect(m_viewer, SIGNAL(aboutToBeDestroyed()), this,
+                 SLOT(onViewerAboutToBeDestroyed()));
     }
     viewerChanged = true;
   }
@@ -514,6 +512,8 @@ void FilmstripFrames::getViewer() {
   if (m_viewer && viewerChanged) {
     connect(m_viewer, SIGNAL(onZoomChanged()), this, SLOT(update()));
     connect(m_viewer, SIGNAL(refreshNavi()), this, SLOT(update()));
+    connect(m_viewer, SIGNAL(aboutToBeDestroyed()), this,
+            SLOT(onViewerAboutToBeDestroyed()));
     update();
   }
 }
@@ -1495,6 +1495,16 @@ void FilmstripFrames::inbetween() {
   FilmstripCmd::inbetween(getLevel(), range.first, range.second, interpolation);
 }
 
+//-----------------------------------------------------------------------------
+
+void FilmstripFrames::onViewerAboutToBeDestroyed() {
+  if (m_viewer) {
+    disconnect(m_viewer, SIGNAL(onZoomChanged()), this, SLOT(update()));
+    disconnect(m_viewer, SIGNAL(refreshNavi()), this, SLOT(update()));
+    m_viewer = nullptr;
+  }
+}
+
 //=============================================================================
 // Filmstrip
 //-----------------------------------------------------------------------------
diff --git a/toonz/sources/toonz/filmstrip.h b/toonz/sources/toonz/filmstrip.h
index fb3cb97..57a4416 100644
--- a/toonz/sources/toonz/filmstrip.h
+++ b/toonz/sources/toonz/filmstrip.h
@@ -172,6 +172,7 @@ protected slots:
   void comboBoxToggled(bool);
   void navigatorToggled(bool);
   void levelSelected(int);
+  void onViewerAboutToBeDestroyed();
 
 private:
   // QSS Properties
diff --git a/toonz/sources/toonz/sceneviewer.cpp b/toonz/sources/toonz/sceneviewer.cpp
index edfbd25..4316da2 100644
--- a/toonz/sources/toonz/sceneviewer.cpp
+++ b/toonz/sources/toonz/sceneviewer.cpp
@@ -831,6 +831,9 @@ void SceneViewer::setVisual(const ImagePainter::VisualSettings &settings) {
 //-----------------------------------------------------------------------------
 
 SceneViewer::~SceneViewer() {
+  // notify FilmStripFrames and safely disconnect with this
+  emit aboutToBeDestroyed();
+
   if (m_fbo) delete m_fbo;
 
   // release all the registered context (once when exit the software)
diff --git a/toonz/sources/toonz/sceneviewer.h b/toonz/sources/toonz/sceneviewer.h
index c52d8e3..d200041 100644
--- a/toonz/sources/toonz/sceneviewer.h
+++ b/toonz/sources/toonz/sceneviewer.h
@@ -460,6 +460,8 @@ signals:
   void refreshNavi();
   // for updating the titlebar
   void previewToggled();
+  // to notify FilmStripFrames and safely disconnect with this
+  void aboutToBeDestroyed();
 };
 
 // Functions