diff --git a/app/lib/widget/viewer/view.dart b/app/lib/widget/viewer/view.dart
index 743f8e8e..609430ff 100644
--- a/app/lib/widget/viewer/view.dart
+++ b/app/lib/widget/viewer/view.dart
@@ -163,7 +163,7 @@ class _PageViewState extends State<_PageView> {
       });
     } else {
       WidgetsBinding.instance.addPostFrameCallback((_) {
-        if (mounted) {
+        if (mounted && _scrollController.hasClients) {
           _scrollController.jumpTo(0);
         }
       });
diff --git a/app/lib/widget/zoomable_viewer.dart b/app/lib/widget/zoomable_viewer.dart
index b0a293f6..cd590326 100644
--- a/app/lib/widget/zoomable_viewer.dart
+++ b/app/lib/widget/zoomable_viewer.dart
@@ -87,9 +87,10 @@ class _ZoomableViewerState extends State<ZoomableViewer>
   }
 
   void _setIsZooming(bool flag) {
-    setState(() {
-      _isZooming = flag;
-    });
+    _isZooming = flag;
+    if (mounted) {
+      setState(() {});
+    }
     final next = _isZoomed;
     if (next != _wasZoomed) {
       _wasZoomed = next;